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36 commits

Author SHA1 Message Date
Chen Yu
70fb5ccf2e sched/fair: Introduce SIS_UTIL to search idle CPU based on sum of util_avg
[Problem Statement]
select_idle_cpu() might spend too much time searching for an idle CPU,
when the system is overloaded.

The following histogram is the time spent in select_idle_cpu(),
when running 224 instances of netperf on a system with 112 CPUs
per LLC domain:

@usecs:
[0]                  533 |                                                    |
[1]                 5495 |                                                    |
[2, 4)             12008 |                                                    |
[4, 8)            239252 |                                                    |
[8, 16)          4041924 |@@@@@@@@@@@@@@                                      |
[16, 32)        12357398 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@         |
[32, 64)        14820255 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[64, 128)       13047682 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@       |
[128, 256)       8235013 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@                        |
[256, 512)       4507667 |@@@@@@@@@@@@@@@                                     |
[512, 1K)        2600472 |@@@@@@@@@                                           |
[1K, 2K)          927912 |@@@                                                 |
[2K, 4K)          218720 |                                                    |
[4K, 8K)           98161 |                                                    |
[8K, 16K)          37722 |                                                    |
[16K, 32K)          6715 |                                                    |
[32K, 64K)           477 |                                                    |
[64K, 128K)            7 |                                                    |

netperf latency usecs:
=======
case            	load    	    Lat_99th	    std%
TCP_RR          	thread-224	      257.39	(  0.21)

The time spent in select_idle_cpu() is visible to netperf and might have a negative
impact.

[Symptom analysis]
The patch [1] from Mel Gorman has been applied to track the efficiency
of select_idle_sibling. Copy the indicators here:

SIS Search Efficiency(se_eff%):
        A ratio expressed as a percentage of runqueues scanned versus
        idle CPUs found. A 100% efficiency indicates that the target,
        prev or recent CPU of a task was idle at wakeup. The lower the
        efficiency, the more runqueues were scanned before an idle CPU
        was found.

SIS Domain Search Efficiency(dom_eff%):
        Similar, except only for the slower SIS
	patch.

SIS Fast Success Rate(fast_rate%):
        Percentage of SIS that used target, prev or
	recent CPUs.

SIS Success rate(success_rate%):
        Percentage of scans that found an idle CPU.

The test is based on Aubrey's schedtests tool, including netperf, hackbench,
schbench and tbench.

Test on vanilla kernel:
schedstat_parse.py -f netperf_vanilla.log
case	        load	    se_eff%	    dom_eff%	  fast_rate%	success_rate%
TCP_RR	   28 threads	     99.978	      18.535	      99.995	     100.000
TCP_RR	   56 threads	     99.397	       5.671	      99.964	     100.000
TCP_RR	   84 threads	     21.721	       6.818	      73.632	     100.000
TCP_RR	  112 threads	     12.500	       5.533	      59.000	     100.000
TCP_RR	  140 threads	      8.524	       4.535	      49.020	     100.000
TCP_RR	  168 threads	      6.438	       3.945	      40.309	      99.999
TCP_RR	  196 threads	      5.397	       3.718	      32.320	      99.982
TCP_RR	  224 threads	      4.874	       3.661	      25.775	      99.767
UDP_RR	   28 threads	     99.988	      17.704	      99.997	     100.000
UDP_RR	   56 threads	     99.528	       5.977	      99.970	     100.000
UDP_RR	   84 threads	     24.219	       6.992	      76.479	     100.000
UDP_RR	  112 threads	     13.907	       5.706	      62.538	     100.000
UDP_RR	  140 threads	      9.408	       4.699	      52.519	     100.000
UDP_RR	  168 threads	      7.095	       4.077	      44.352	     100.000
UDP_RR	  196 threads	      5.757	       3.775	      35.764	      99.991
UDP_RR	  224 threads	      5.124	       3.704	      28.748	      99.860

schedstat_parse.py -f schbench_vanilla.log
(each group has 28 tasks)
case	        load	    se_eff%	    dom_eff%	  fast_rate%	success_rate%
normal	   1   mthread	     99.152	       6.400	      99.941	     100.000
normal	   2   mthreads	     97.844	       4.003	      99.908	     100.000
normal	   3   mthreads	     96.395	       2.118	      99.917	      99.998
normal	   4   mthreads	     55.288	       1.451	      98.615	      99.804
normal	   5   mthreads	      7.004	       1.870	      45.597	      61.036
normal	   6   mthreads	      3.354	       1.346	      20.777	      34.230
normal	   7   mthreads	      2.183	       1.028	      11.257	      21.055
normal	   8   mthreads	      1.653	       0.825	       7.849	      15.549

schedstat_parse.py -f hackbench_vanilla.log
(each group has 28 tasks)
case			load	        se_eff%	    dom_eff%	  fast_rate%	success_rate%
process-pipe	     1 group	         99.991	       7.692	      99.999	     100.000
process-pipe	    2 groups	         99.934	       4.615	      99.997	     100.000
process-pipe	    3 groups	         99.597	       3.198	      99.987	     100.000
process-pipe	    4 groups	         98.378	       2.464	      99.958	     100.000
process-pipe	    5 groups	         27.474	       3.653	      89.811	      99.800
process-pipe	    6 groups	         20.201	       4.098	      82.763	      99.570
process-pipe	    7 groups	         16.423	       4.156	      77.398	      99.316
process-pipe	    8 groups	         13.165	       3.920	      72.232	      98.828
process-sockets	     1 group	         99.977	       5.882	      99.999	     100.000
process-sockets	    2 groups	         99.927	       5.505	      99.996	     100.000
process-sockets	    3 groups	         99.397	       3.250	      99.980	     100.000
process-sockets	    4 groups	         79.680	       4.258	      98.864	      99.998
process-sockets	    5 groups	          7.673	       2.503	      63.659	      92.115
process-sockets	    6 groups	          4.642	       1.584	      58.946	      88.048
process-sockets	    7 groups	          3.493	       1.379	      49.816	      81.164
process-sockets	    8 groups	          3.015	       1.407	      40.845	      75.500
threads-pipe	     1 group	         99.997	       0.000	     100.000	     100.000
threads-pipe	    2 groups	         99.894	       2.932	      99.997	     100.000
threads-pipe	    3 groups	         99.611	       4.117	      99.983	     100.000
threads-pipe	    4 groups	         97.703	       2.624	      99.937	     100.000
threads-pipe	    5 groups	         22.919	       3.623	      87.150	      99.764
threads-pipe	    6 groups	         18.016	       4.038	      80.491	      99.557
threads-pipe	    7 groups	         14.663	       3.991	      75.239	      99.247
threads-pipe	    8 groups	         12.242	       3.808	      70.651	      98.644
threads-sockets	     1 group	         99.990	       6.667	      99.999	     100.000
threads-sockets	    2 groups	         99.940	       5.114	      99.997	     100.000
threads-sockets	    3 groups	         99.469	       4.115	      99.977	     100.000
threads-sockets	    4 groups	         87.528	       4.038	      99.400	     100.000
threads-sockets	    5 groups	          6.942	       2.398	      59.244	      88.337
threads-sockets	    6 groups	          4.359	       1.954	      49.448	      87.860
threads-sockets	    7 groups	          2.845	       1.345	      41.198	      77.102
threads-sockets	    8 groups	          2.871	       1.404	      38.512	      74.312

schedstat_parse.py -f tbench_vanilla.log
case			load	      se_eff%	    dom_eff%	  fast_rate%	success_rate%
loopback	  28 threads	       99.976	      18.369	      99.995	     100.000
loopback	  56 threads	       99.222	       7.799	      99.934	     100.000
loopback	  84 threads	       19.723	       6.819	      70.215	     100.000
loopback	 112 threads	       11.283	       5.371	      55.371	      99.999
loopback	 140 threads	        0.000	       0.000	       0.000	       0.000
loopback	 168 threads	        0.000	       0.000	       0.000	       0.000
loopback	 196 threads	        0.000	       0.000	       0.000	       0.000
loopback	 224 threads	        0.000	       0.000	       0.000	       0.000

According to the test above, if the system becomes busy, the
SIS Search Efficiency(se_eff%) drops significantly. Although some
benchmarks would finally find an idle CPU(success_rate% = 100%), it is
doubtful whether it is worth it to search the whole LLC domain.

[Proposal]
It would be ideal to have a crystal ball to answer this question:
How many CPUs must a wakeup path walk down, before it can find an idle
CPU? Many potential metrics could be used to predict the number.
One candidate is the sum of util_avg in this LLC domain. The benefit
of choosing util_avg is that it is a metric of accumulated historic
activity, which seems to be smoother than instantaneous metrics
(such as rq->nr_running). Besides, choosing the sum of util_avg
would help predict the load of the LLC domain more precisely, because
SIS_PROP uses one CPU's idle time to estimate the total LLC domain idle
time.

In summary, the lower the util_avg is, the more select_idle_cpu()
should scan for idle CPU, and vice versa. When the sum of util_avg
in this LLC domain hits 85% or above, the scan stops. The reason to
choose 85% as the threshold is that this is the imbalance_pct(117)
when a LLC sched group is overloaded.

Introduce the quadratic function:

y = SCHED_CAPACITY_SCALE - p * x^2
and y'= y / SCHED_CAPACITY_SCALE

x is the ratio of sum_util compared to the CPU capacity:
x = sum_util / (llc_weight * SCHED_CAPACITY_SCALE)
y' is the ratio of CPUs to be scanned in the LLC domain,
and the number of CPUs to scan is calculated by:

nr_scan = llc_weight * y'

Choosing quadratic function is because:
[1] Compared to the linear function, it scans more aggressively when the
    sum_util is low.
[2] Compared to the exponential function, it is easier to calculate.
[3] It seems that there is no accurate mapping between the sum of util_avg
    and the number of CPUs to be scanned. Use heuristic scan for now.

For a platform with 112 CPUs per LLC, the number of CPUs to scan is:
sum_util%   0    5   15   25  35  45  55   65   75   85   86 ...
scan_nr   112  111  108  102  93  81  65   47   25    1    0 ...

For a platform with 16 CPUs per LLC, the number of CPUs to scan is:
sum_util%   0    5   15   25  35  45  55   65   75   85   86 ...
scan_nr    16   15   15   14  13  11   9    6    3    0    0 ...

Furthermore, to minimize the overhead of calculating the metrics in
select_idle_cpu(), borrow the statistics from periodic load balance.
As mentioned by Abel, on a platform with 112 CPUs per LLC, the
sum_util calculated by periodic load balance after 112 ms would
decay to about 0.5 * 0.5 * 0.5 * 0.7 = 8.75%, thus bringing a delay
in reflecting the latest utilization. But it is a trade-off.
Checking the util_avg in newidle load balance would be more frequent,
but it brings overhead - multiple CPUs write/read the per-LLC shared
variable and introduces cache contention. Tim also mentioned that,
it is allowed to be non-optimal in terms of scheduling for the
short-term variations, but if there is a long-term trend in the load
behavior, the scheduler can adjust for that.

When SIS_UTIL is enabled, the select_idle_cpu() uses the nr_scan
calculated by SIS_UTIL instead of the one from SIS_PROP. As Peter and
Mel suggested, SIS_UTIL should be enabled by default.

This patch is based on the util_avg, which is very sensitive to the
CPU frequency invariance. There is an issue that, when the max frequency
has been clamp, the util_avg would decay insanely fast when
the CPU is idle. Commit addca28512 ("cpufreq: intel_pstate: Handle no_turbo
in frequency invariance") could be used to mitigate this symptom, by adjusting
the arch_max_freq_ratio when turbo is disabled. But this issue is still
not thoroughly fixed, because the current code is unaware of the user-specified
max CPU frequency.

[Test result]

netperf and tbench were launched with 25% 50% 75% 100% 125% 150%
175% 200% of CPU number respectively. Hackbench and schbench were launched
by 1, 2 ,4, 8 groups. Each test lasts for 100 seconds and repeats 3 times.

The following is the benchmark result comparison between
baseline:vanilla v5.19-rc1 and compare:patched kernel. Positive compare%
indicates better performance.

Each netperf test is a:
netperf -4 -H 127.0.1 -t TCP/UDP_RR -c -C -l 100
netperf.throughput
=======
case            	load    	baseline(std%)	compare%( std%)
TCP_RR          	28 threads	 1.00 (  0.34)	 -0.16 (  0.40)
TCP_RR          	56 threads	 1.00 (  0.19)	 -0.02 (  0.20)
TCP_RR          	84 threads	 1.00 (  0.39)	 -0.47 (  0.40)
TCP_RR          	112 threads	 1.00 (  0.21)	 -0.66 (  0.22)
TCP_RR          	140 threads	 1.00 (  0.19)	 -0.69 (  0.19)
TCP_RR          	168 threads	 1.00 (  0.18)	 -0.48 (  0.18)
TCP_RR          	196 threads	 1.00 (  0.16)	+194.70 ( 16.43)
TCP_RR          	224 threads	 1.00 (  0.16)	+197.30 (  7.85)
UDP_RR          	28 threads	 1.00 (  0.37)	 +0.35 (  0.33)
UDP_RR          	56 threads	 1.00 ( 11.18)	 -0.32 (  0.21)
UDP_RR          	84 threads	 1.00 (  1.46)	 -0.98 (  0.32)
UDP_RR          	112 threads	 1.00 ( 28.85)	 -2.48 ( 19.61)
UDP_RR          	140 threads	 1.00 (  0.70)	 -0.71 ( 14.04)
UDP_RR          	168 threads	 1.00 ( 14.33)	 -0.26 ( 11.16)
UDP_RR          	196 threads	 1.00 ( 12.92)	+186.92 ( 20.93)
UDP_RR          	224 threads	 1.00 ( 11.74)	+196.79 ( 18.62)

Take the 224 threads as an example, the SIS search metrics changes are
illustrated below:

    vanilla                    patched
   4544492          +237.5%   15338634        sched_debug.cpu.sis_domain_search.avg
     38539        +39686.8%   15333634        sched_debug.cpu.sis_failed.avg
  128300000          -87.9%   15551326        sched_debug.cpu.sis_scanned.avg
   5842896          +162.7%   15347978        sched_debug.cpu.sis_search.avg

There is -87.9% less CPU scans after patched, which indicates lower overhead.
Besides, with this patch applied, there is -13% less rq lock contention
in perf-profile.calltrace.cycles-pp._raw_spin_lock.raw_spin_rq_lock_nested
.try_to_wake_up.default_wake_function.woken_wake_function.
This might help explain the performance improvement - Because this patch allows
the waking task to remain on the previous CPU, rather than grabbing other CPUs'
lock.

Each hackbench test is a:
hackbench -g $job --process/threads --pipe/sockets -l 1000000 -s 100
hackbench.throughput
=========
case            	load    	baseline(std%)	compare%( std%)
process-pipe    	1 group 	 1.00 (  1.29)	 +0.57 (  0.47)
process-pipe    	2 groups 	 1.00 (  0.27)	 +0.77 (  0.81)
process-pipe    	4 groups 	 1.00 (  0.26)	 +1.17 (  0.02)
process-pipe    	8 groups 	 1.00 (  0.15)	 -4.79 (  0.02)
process-sockets 	1 group 	 1.00 (  0.63)	 -0.92 (  0.13)
process-sockets 	2 groups 	 1.00 (  0.03)	 -0.83 (  0.14)
process-sockets 	4 groups 	 1.00 (  0.40)	 +5.20 (  0.26)
process-sockets 	8 groups 	 1.00 (  0.04)	 +3.52 (  0.03)
threads-pipe    	1 group 	 1.00 (  1.28)	 +0.07 (  0.14)
threads-pipe    	2 groups 	 1.00 (  0.22)	 -0.49 (  0.74)
threads-pipe    	4 groups 	 1.00 (  0.05)	 +1.88 (  0.13)
threads-pipe    	8 groups 	 1.00 (  0.09)	 -4.90 (  0.06)
threads-sockets 	1 group 	 1.00 (  0.25)	 -0.70 (  0.53)
threads-sockets 	2 groups 	 1.00 (  0.10)	 -0.63 (  0.26)
threads-sockets 	4 groups 	 1.00 (  0.19)	+11.92 (  0.24)
threads-sockets 	8 groups 	 1.00 (  0.08)	 +4.31 (  0.11)

Each tbench test is a:
tbench -t 100 $job 127.0.0.1
tbench.throughput
======
case            	load    	baseline(std%)	compare%( std%)
loopback        	28 threads	 1.00 (  0.06)	 -0.14 (  0.09)
loopback        	56 threads	 1.00 (  0.03)	 -0.04 (  0.17)
loopback        	84 threads	 1.00 (  0.05)	 +0.36 (  0.13)
loopback        	112 threads	 1.00 (  0.03)	 +0.51 (  0.03)
loopback        	140 threads	 1.00 (  0.02)	 -1.67 (  0.19)
loopback        	168 threads	 1.00 (  0.38)	 +1.27 (  0.27)
loopback        	196 threads	 1.00 (  0.11)	 +1.34 (  0.17)
loopback        	224 threads	 1.00 (  0.11)	 +1.67 (  0.22)

Each schbench test is a:
schbench -m $job -t 28 -r 100 -s 30000 -c 30000
schbench.latency_90%_us
========
case            	load    	baseline(std%)	compare%( std%)
normal          	1 mthread	 1.00 ( 31.22)	 -7.36 ( 20.25)*
normal          	2 mthreads	 1.00 (  2.45)	 -0.48 (  1.79)
normal          	4 mthreads	 1.00 (  1.69)	 +0.45 (  0.64)
normal          	8 mthreads	 1.00 (  5.47)	 +9.81 ( 14.28)

*Consider the Standard Deviation, this -7.36% regression might not be valid.

Also, a OLTP workload with a commercial RDBMS has been tested, and there
is no significant change.

There were concerns that unbalanced tasks among CPUs would cause problems.
For example, suppose the LLC domain is composed of 8 CPUs, and 7 tasks are
bound to CPU0~CPU6, while CPU7 is idle:

          CPU0    CPU1    CPU2    CPU3    CPU4    CPU5    CPU6    CPU7
util_avg  1024    1024    1024    1024    1024    1024    1024    0

Since the util_avg ratio is 87.5%( = 7/8 ), which is higher than 85%,
select_idle_cpu() will not scan, thus CPU7 is undetected during scan.
But according to Mel, it is unlikely the CPU7 will be idle all the time
because CPU7 could pull some tasks via CPU_NEWLY_IDLE.

lkp(kernel test robot) has reported a regression on stress-ng.sock on a
very busy system. According to the sched_debug statistics, it might be caused
by SIS_UTIL terminates the scan and chooses a previous CPU earlier, and this
might introduce more context switch, especially involuntary preemption, which
impacts a busy stress-ng. This regression has shown that, not all benchmarks
in every scenario benefit from idle CPU scan limit, and it needs further
investigation.

Besides, there is slight regression in hackbench's 16 groups case when the
LLC domain has 16 CPUs. Prateek mentioned that we should scan aggressively
in an LLC domain with 16 CPUs. Because the cost to search for an idle one
among 16 CPUs is negligible. The current patch aims to propose a generic
solution and only considers the util_avg. Something like the below could
be applied on top of the current patch to fulfill the requirement:

	if (llc_weight <= 16)
		nr_scan = nr_scan * 32 / llc_weight;

For LLC domain with 16 CPUs, the nr_scan will be expanded to 2 times large.
The smaller the CPU number this LLC domain has, the larger nr_scan will be
expanded. This needs further investigation.

There is also ongoing work[2] from Abel to filter out the busy CPUs during
wakeup, to further speed up the idle CPU scan. And it could be a following-up
optimization on top of this change.

Suggested-by: Tim Chen <tim.c.chen@intel.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Yicong Yang <yangyicong@hisilicon.com>
Tested-by: Mohini Narkhede <mohini.narkhede@intel.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20220612163428.849378-1-yu.c.chen@intel.com
2022-06-28 09:08:30 +02:00
Mel Gorman
e496132ebe sched/fair: Adjust the allowed NUMA imbalance when SD_NUMA spans multiple LLCs
Commit 7d2b5dd0bc ("sched/numa: Allow a floating imbalance between NUMA
nodes") allowed an imbalance between NUMA nodes such that communicating
tasks would not be pulled apart by the load balancer. This works fine when
there is a 1:1 relationship between LLC and node but can be suboptimal
for multiple LLCs if independent tasks prematurely use CPUs sharing cache.

Zen* has multiple LLCs per node with local memory channels and due to
the allowed imbalance, it's far harder to tune some workloads to run
optimally than it is on hardware that has 1 LLC per node. This patch
allows an imbalance to exist up to the point where LLCs should be balanced
between nodes.

On a Zen3 machine running STREAM parallelised with OMP to have on instance
per LLC the results and without binding, the results are

                            5.17.0-rc0             5.17.0-rc0
                               vanilla       sched-numaimb-v6
MB/sec copy-16    162596.94 (   0.00%)   580559.74 ( 257.05%)
MB/sec scale-16   136901.28 (   0.00%)   374450.52 ( 173.52%)
MB/sec add-16     157300.70 (   0.00%)   564113.76 ( 258.62%)
MB/sec triad-16   151446.88 (   0.00%)   564304.24 ( 272.61%)

STREAM can use directives to force the spread if the OpenMP is new
enough but that doesn't help if an application uses threads and
it's not known in advance how many threads will be created.

Coremark is a CPU and cache intensive benchmark parallelised with
threads. When running with 1 thread per core, the vanilla kernel
allows threads to contend on cache. With the patch;

                               5.17.0-rc0             5.17.0-rc0
                                  vanilla       sched-numaimb-v5
Min       Score-16   368239.36 (   0.00%)   389816.06 (   5.86%)
Hmean     Score-16   388607.33 (   0.00%)   427877.08 *  10.11%*
Max       Score-16   408945.69 (   0.00%)   481022.17 (  17.62%)
Stddev    Score-16    15247.04 (   0.00%)    24966.82 ( -63.75%)
CoeffVar  Score-16        3.92 (   0.00%)        5.82 ( -48.48%)

It can also make a big difference for semi-realistic workloads
like specjbb which can execute arbitrary numbers of threads without
advance knowledge of how they should be placed. Even in cases where
the average performance is neutral, the results are more stable.

                               5.17.0-rc0             5.17.0-rc0
                                  vanilla       sched-numaimb-v6
Hmean     tput-1      71631.55 (   0.00%)    73065.57 (   2.00%)
Hmean     tput-8     582758.78 (   0.00%)   556777.23 (  -4.46%)
Hmean     tput-16   1020372.75 (   0.00%)  1009995.26 (  -1.02%)
Hmean     tput-24   1416430.67 (   0.00%)  1398700.11 (  -1.25%)
Hmean     tput-32   1687702.72 (   0.00%)  1671357.04 (  -0.97%)
Hmean     tput-40   1798094.90 (   0.00%)  2015616.46 *  12.10%*
Hmean     tput-48   1972731.77 (   0.00%)  2333233.72 (  18.27%)
Hmean     tput-56   2386872.38 (   0.00%)  2759483.38 (  15.61%)
Hmean     tput-64   2909475.33 (   0.00%)  2925074.69 (   0.54%)
Hmean     tput-72   2585071.36 (   0.00%)  2962443.97 (  14.60%)
Hmean     tput-80   2994387.24 (   0.00%)  3015980.59 (   0.72%)
Hmean     tput-88   3061408.57 (   0.00%)  3010296.16 (  -1.67%)
Hmean     tput-96   3052394.82 (   0.00%)  2784743.41 (  -8.77%)
Hmean     tput-104  2997814.76 (   0.00%)  2758184.50 (  -7.99%)
Hmean     tput-112  2955353.29 (   0.00%)  2859705.09 (  -3.24%)
Hmean     tput-120  2889770.71 (   0.00%)  2764478.46 (  -4.34%)
Hmean     tput-128  2871713.84 (   0.00%)  2750136.73 (  -4.23%)
Stddev    tput-1       5325.93 (   0.00%)     2002.53 (  62.40%)
Stddev    tput-8       6630.54 (   0.00%)    10905.00 ( -64.47%)
Stddev    tput-16     25608.58 (   0.00%)     6851.16 (  73.25%)
Stddev    tput-24     12117.69 (   0.00%)     4227.79 (  65.11%)
Stddev    tput-32     27577.16 (   0.00%)     8761.05 (  68.23%)
Stddev    tput-40     59505.86 (   0.00%)     2048.49 (  96.56%)
Stddev    tput-48    168330.30 (   0.00%)    93058.08 (  44.72%)
Stddev    tput-56    219540.39 (   0.00%)    30687.02 (  86.02%)
Stddev    tput-64    121750.35 (   0.00%)     9617.36 (  92.10%)
Stddev    tput-72    223387.05 (   0.00%)    34081.13 (  84.74%)
Stddev    tput-80    128198.46 (   0.00%)    22565.19 (  82.40%)
Stddev    tput-88    136665.36 (   0.00%)    27905.97 (  79.58%)
Stddev    tput-96    111925.81 (   0.00%)    99615.79 (  11.00%)
Stddev    tput-104   146455.96 (   0.00%)    28861.98 (  80.29%)
Stddev    tput-112    88740.49 (   0.00%)    58288.23 (  34.32%)
Stddev    tput-120   186384.86 (   0.00%)    45812.03 (  75.42%)
Stddev    tput-128    78761.09 (   0.00%)    57418.48 (  27.10%)

Similarly, for embarassingly parallel problems like NPB-ep, there are
improvements due to better spreading across LLC when the machine is not
fully utilised.

                              vanilla       sched-numaimb-v6
Min       ep.D       31.79 (   0.00%)       26.11 (  17.87%)
Amean     ep.D       31.86 (   0.00%)       26.17 *  17.86%*
Stddev    ep.D        0.07 (   0.00%)        0.05 (  24.41%)
CoeffVar  ep.D        0.22 (   0.00%)        0.20 (   7.97%)
Max       ep.D       31.93 (   0.00%)       26.21 (  17.91%)

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20220208094334.16379-3-mgorman@techsingularity.net
2022-02-11 23:30:08 +01:00
Lukasz Luba
7e97b3dc25 arch_topology: Remove unused topology_set_thermal_pressure() and related
There is no need of this function (and related) since code has been
converted to use the new arch_update_thermal_pressure() API. The old
code can be removed.

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
2021-11-23 15:10:26 +05:30
Lukasz Luba
c214f12416 arch_topology: Introduce thermal pressure update function
The thermal pressure is a mechanism which is used for providing
information about reduced CPU performance to the scheduler. Usually code
has to convert the value from frequency units into capacity units,
which are understandable by the scheduler. Create a common conversion code
which can be just used via a handy API.

Internally, the topology_update_thermal_pressure() operates on frequency
in MHz and max CPU frequency is taken from 'freq_factor' (per-cpu).

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Thara Gopinath <thara.gopinath@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
2021-11-23 15:10:26 +05:30
Vincent Guittot
e60b56e46b sched/fair: Wait before decaying max_newidle_lb_cost
Decay max_newidle_lb_cost only when it has not been updated for a while
and ensure to not decay a recently changed value.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20211019123537.17146-4-vincent.guittot@linaro.org
2021-10-31 11:11:38 +01:00
Barry Song
778c558f49 sched: Add cluster scheduler level in core and related Kconfig for ARM64
This patch adds scheduler level for clusters and automatically enables
the load balance among clusters. It will directly benefit a lot of
workload which loves more resources such as memory bandwidth, caches.

Testing has widely been done in two different hardware configurations of
Kunpeng920:

 24 cores in one NUMA(6 clusters in each NUMA node);
 32 cores in one NUMA(8 clusters in each NUMA node)

Workload is running on either one NUMA node or four NUMA nodes, thus,
this can estimate the effect of cluster spreading w/ and w/o NUMA load
balance.

* Stream benchmark:

4threads stream (on 1NUMA * 24cores = 24cores)
                stream                 stream
                w/o patch              w/ patch
MB/sec copy     29929.64 (   0.00%)    32932.68 (  10.03%)
MB/sec scale    29861.10 (   0.00%)    32710.58 (   9.54%)
MB/sec add      27034.42 (   0.00%)    32400.68 (  19.85%)
MB/sec triad    27225.26 (   0.00%)    31965.36 (  17.41%)

6threads stream (on 1NUMA * 24cores = 24cores)
                stream                 stream
                w/o patch              w/ patch
MB/sec copy     40330.24 (   0.00%)    42377.68 (   5.08%)
MB/sec scale    40196.42 (   0.00%)    42197.90 (   4.98%)
MB/sec add      37427.00 (   0.00%)    41960.78 (  12.11%)
MB/sec triad    37841.36 (   0.00%)    42513.64 (  12.35%)

12threads stream (on 1NUMA * 24cores = 24cores)
                stream                 stream
                w/o patch              w/ patch
MB/sec copy     52639.82 (   0.00%)    53818.04 (   2.24%)
MB/sec scale    52350.30 (   0.00%)    53253.38 (   1.73%)
MB/sec add      53607.68 (   0.00%)    55198.82 (   2.97%)
MB/sec triad    54776.66 (   0.00%)    56360.40 (   2.89%)

Thus, it could help memory-bound workload especially under medium load.
Similar improvement is also seen in lkp-pbzip2:

* lkp-pbzip2 benchmark

2-96 threads (on 4NUMA * 24cores = 96cores)
                  lkp-pbzip2              lkp-pbzip2
                  w/o patch               w/ patch
Hmean     tput-2   11062841.57 (   0.00%)  11341817.51 *   2.52%*
Hmean     tput-5   26815503.70 (   0.00%)  27412872.65 *   2.23%*
Hmean     tput-8   41873782.21 (   0.00%)  43326212.92 *   3.47%*
Hmean     tput-12  61875980.48 (   0.00%)  64578337.51 *   4.37%*
Hmean     tput-21 105814963.07 (   0.00%) 111381851.01 *   5.26%*
Hmean     tput-30 150349470.98 (   0.00%) 156507070.73 *   4.10%*
Hmean     tput-48 237195937.69 (   0.00%) 242353597.17 *   2.17%*
Hmean     tput-79 360252509.37 (   0.00%) 362635169.23 *   0.66%*
Hmean     tput-96 394571737.90 (   0.00%) 400952978.48 *   1.62%*

2-24 threads (on 1NUMA * 24cores = 24cores)
                 lkp-pbzip2               lkp-pbzip2
                 w/o patch                w/ patch
Hmean     tput-2   11071705.49 (   0.00%)  11296869.10 *   2.03%*
Hmean     tput-4   20782165.19 (   0.00%)  21949232.15 *   5.62%*
Hmean     tput-6   30489565.14 (   0.00%)  33023026.96 *   8.31%*
Hmean     tput-8   40376495.80 (   0.00%)  42779286.27 *   5.95%*
Hmean     tput-12  61264033.85 (   0.00%)  62995632.78 *   2.83%*
Hmean     tput-18  86697139.39 (   0.00%)  86461545.74 (  -0.27%)
Hmean     tput-24 104854637.04 (   0.00%) 104522649.46 *  -0.32%*

In the case of 6 threads and 8 threads, we see the greatest performance
improvement.

Similar improvement can be seen on lkp-pixz though the improvement is
smaller:

* lkp-pixz benchmark

2-24 threads lkp-pixz (on 1NUMA * 24cores = 24cores)
                  lkp-pixz               lkp-pixz
                  w/o patch              w/ patch
Hmean     tput-2   6486981.16 (   0.00%)  6561515.98 *   1.15%*
Hmean     tput-4  11645766.38 (   0.00%) 11614628.43 (  -0.27%)
Hmean     tput-6  15429943.96 (   0.00%) 15957350.76 *   3.42%*
Hmean     tput-8  19974087.63 (   0.00%) 20413746.98 *   2.20%*
Hmean     tput-12 28172068.18 (   0.00%) 28751997.06 *   2.06%*
Hmean     tput-18 39413409.54 (   0.00%) 39896830.55 *   1.23%*
Hmean     tput-24 49101815.85 (   0.00%) 49418141.47 *   0.64%*

* SPECrate benchmark

4,8,16 copies mcf_r(on 1NUMA * 32cores = 32cores)
		Base     	 	Base
		Run Time   	 	Rate
		-------  	 	---------
4 Copies	w/o 580 (w/ 570)       	w/o 11.1 (w/ 11.3)
8 Copies	w/o 647 (w/ 605)       	w/o 20.0 (w/ 21.4, +7%)
16 Copies	w/o 844 (w/ 844)       	w/o 30.6 (w/ 30.6)

32 Copies(on 4NUMA * 32 cores = 128cores)
[w/o patch]
                 Base     Base        Base
Benchmarks       Copies  Run Time     Rate
--------------- -------  ---------  ---------
500.perlbench_r      32        584       87.2  *
502.gcc_r            32        503       90.2  *
505.mcf_r            32        745       69.4  *
520.omnetpp_r        32       1031       40.7  *
523.xalancbmk_r      32        597       56.6  *
525.x264_r            1         --            CE
531.deepsjeng_r      32        336      109    *
541.leela_r          32        556       95.4  *
548.exchange2_r      32        513      163    *
557.xz_r             32        530       65.2  *
 Est. SPECrate2017_int_base              80.3

[w/ patch]
                  Base     Base        Base
Benchmarks       Copies  Run Time     Rate
--------------- -------  ---------  ---------
500.perlbench_r      32        580      87.8 (+0.688%)  *
502.gcc_r            32        477      95.1 (+5.432%)  *
505.mcf_r            32        644      80.3 (+13.574%) *
520.omnetpp_r        32        942      44.6 (+9.58%)   *
523.xalancbmk_r      32        560      60.4 (+6.714%%) *
525.x264_r            1         --           CE
531.deepsjeng_r      32        337      109  (+0.000%) *
541.leela_r          32        554      95.6 (+0.210%) *
548.exchange2_r      32        515      163  (+0.000%) *
557.xz_r             32        524      66.0 (+1.227%) *
 Est. SPECrate2017_int_base              83.7 (+4.062%)

On the other hand, it is slightly helpful to CPU-bound tasks like
kernbench:

* 24-96 threads kernbench (on 4NUMA * 24cores = 96cores)
                     kernbench              kernbench
                     w/o cluster            w/ cluster
Min       user-24    12054.67 (   0.00%)    12024.19 (   0.25%)
Min       syst-24     1751.51 (   0.00%)     1731.68 (   1.13%)
Min       elsp-24      600.46 (   0.00%)      598.64 (   0.30%)
Min       user-48    12361.93 (   0.00%)    12315.32 (   0.38%)
Min       syst-48     1917.66 (   0.00%)     1892.73 (   1.30%)
Min       elsp-48      333.96 (   0.00%)      332.57 (   0.42%)
Min       user-96    12922.40 (   0.00%)    12921.17 (   0.01%)
Min       syst-96     2143.94 (   0.00%)     2110.39 (   1.56%)
Min       elsp-96      211.22 (   0.00%)      210.47 (   0.36%)
Amean     user-24    12063.99 (   0.00%)    12030.78 *   0.28%*
Amean     syst-24     1755.20 (   0.00%)     1735.53 *   1.12%*
Amean     elsp-24      601.60 (   0.00%)      600.19 (   0.23%)
Amean     user-48    12362.62 (   0.00%)    12315.56 *   0.38%*
Amean     syst-48     1921.59 (   0.00%)     1894.95 *   1.39%*
Amean     elsp-48      334.10 (   0.00%)      332.82 *   0.38%*
Amean     user-96    12925.27 (   0.00%)    12922.63 (   0.02%)
Amean     syst-96     2146.66 (   0.00%)     2122.20 *   1.14%*
Amean     elsp-96      211.96 (   0.00%)      211.79 (   0.08%)

Note this patch isn't an universal win, it might hurt those workload
which can benefit from packing. Though tasks which want to take
advantages of lower communication latency of one cluster won't
necessarily been packed in one cluster while kernel is not aware of
clusters, they have some chance to be randomly packed. But this
patch will make them more likely spread.

Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Tested-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2021-10-15 11:25:16 +02:00
Ionela Voinescu
31f6a8c0a4 sched/topology,schedutil: Wrap sched domains rebuild
Add the rebuild_sched_domains_energy() function to wrap the functionality
that rebuilds the scheduling domains if any of the Energy Aware Scheduling
(EAS) initialisation conditions change. This functionality is used when
schedutil is added or removed or when EAS is enabled or disabled
through the sched_energy_aware sysctl.

Therefore, create a single function that is used in both these cases and
that can be later reused.

Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Quentin Perret <qperret@google.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lkml.kernel.org/r/20201027180713.7642-2-ionela.voinescu@arm.com
2020-11-19 11:25:47 +01:00
Valentin Schneider
4fc472f121 sched/topology: Move SD_DEGENERATE_GROUPS_MASK out of linux/sched/topology.h
SD_DEGENERATE_GROUPS_MASK is only useful for sched/topology.c, but still
gets defined for anyone who imports topology.h, leading to a flurry of
unused variable warnings.

Move it out of the header and place it next to the SD degeneration
functions in sched/topology.c.

Fixes: 4ee4ea443a ("sched/topology: Introduce SD metaflag for flags needing > 1 groups")
Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200825133216.9163-2-valentin.schneider@arm.com
2020-08-26 12:41:59 +02:00
Valentin Schneider
8fca9494d4 sched/topology: Move sd_flag_debug out of linux/sched/topology.h
Defining an array in a header imported all over the place clearly is a daft
idea, that still didn't stop me from doing it.

Leave a declaration of sd_flag_debug in topology.h and move its definition
to sched/debug.c.

Fixes: b6e862f386 ("sched/topology: Define and assign sched_domain flag metadata")
Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200825133216.9163-1-valentin.schneider@arm.com
2020-08-26 12:41:59 +02:00
Valentin Schneider
4ee4ea443a sched/topology: Introduce SD metaflag for flags needing > 1 groups
In preparation of cleaning up the sd_degenerate*() functions, mark flags
used in sd_degenerate() with the new SDF_NEEDS_GROUPS flag. With this,
build a compile-time mask of those SD flags.

Note that sd_parent_degenerate() uses an extra flag in its mask,
SD_PREFER_SIBLING, which remains singled out for now.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20200817113003.20802-8-valentin.schneider@arm.com
2020-08-19 10:49:48 +02:00
Valentin Schneider
b6e862f386 sched/topology: Define and assign sched_domain flag metadata
There are some expectations regarding how sched domain flags should be laid
out, but none of them are checked or asserted in
sched_domain_debug_one(). After staring at said flags for a while, I've
come to realize there's two repeating patterns:

- Shared with children: those flags are set from the base CPU domain
  upwards. Any domain that has it set will have it set in its children. It
  hints at "some property holds true / some behaviour is enabled until this
  level".

- Shared with parents: those flags are set from the topmost domain
  downwards. Any domain that has it set will have it set in its parents. It
  hints at "some property isn't visible / some behaviour is disabled until
  this level".

There are two outliers that (currently) do not map to either of these:

o SD_PREFER_SIBLING, which is cleared below levels with
  SD_ASYM_CPUCAPACITY. The change was introduced by commit:

    9c63e84db2 ("sched/core: Disable SD_PREFER_SIBLING on asymmetric CPU capacity domains")

  as it could break misfit migration on some systems. In light of this, we
  might want to change it back to make it fit one of the two categories and
  fix the issue another way.

o SD_ASYM_CPUCAPACITY, which gets set on a single level and isn't
  propagated up nor down. From a topology description point of view, it
  really wants to be SDF_SHARED_PARENT; this will be rectified in a later
  patch.

Tweak the sched_domain flag declaration to assign each flag an expected
layout, and include the rationale for each flag "meta type" assignment as a
comment. Consolidate the flag metadata into an array; the index of a flag's
metadata can easily be found with log2(flag), IOW __ffs(flag).

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20200817113003.20802-5-valentin.schneider@arm.com
2020-08-19 10:49:48 +02:00
Valentin Schneider
d54a9658a7 sched/topology: Split out SD_* flags declaration to its own file
To associate the SD flags with some metadata, we need some more structure
in the way they are declared.

Rather than shove that in a free-standing macro list, move the declaration
in a separate file that can be re-imported with different SD_FLAG
definitions. This is inspired by what is done with the syscall
table (see uapi/asm/unistd.h and sys_call_table).

The value assigned to a given SD flag now depends on the order it appears
in sd_flags.h. No change in functionality.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20200817113003.20802-4-valentin.schneider@arm.com
2020-08-19 10:49:47 +02:00
Valentin Schneider
cfe7ddcbd7 ARM, sched/topology: Remove SD_SHARE_POWERDOMAIN
This flag was introduced in 2014 by commit:

  d77b3ed5c9 ("sched: Add a new SD_SHARE_POWERDOMAIN for sched_domain")

but AFAIA it was never leveraged by the scheduler. The closest thing I can
think of is EAS caring about frequency domains, and it does that by
leveraging performance domains.

Remove the flag. No change in functionality is expected.

Suggested-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/20200817113003.20802-2-valentin.schneider@arm.com
2020-08-19 10:49:47 +02:00
Valentin Schneider
f4470cdf10 sched: Document arch_scale_*_capacity()
Rather that hide their purpose in some dark, damp corner of Documentation/,
add some documentation to the default implementations.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200731192016.7484-2-valentin.schneider@arm.com
2020-08-01 09:19:43 +02:00
Valentin Schneider
25980c7a79 arch_topology, sched/core: Cleanup thermal pressure definition
The following commit:

  14533a16c4 ("thermal/cpu-cooling, sched/core: Move the arch_set_thermal_pressure() API to generic scheduler code")

moved the definition of arch_set_thermal_pressure() to sched/core.c, but
kept its declaration in linux/arch_topology.h. When building e.g. an x86
kernel with CONFIG_SCHED_THERMAL_PRESSURE=y, cpufreq_cooling.c ends up
getting the declaration of arch_set_thermal_pressure() from
include/linux/arch_topology.h, which is somewhat awkward.

On top of this, sched/core.c unconditionally defines
o The thermal_pressure percpu variable
o arch_set_thermal_pressure()

while arch_scale_thermal_pressure() does nothing unless redefined by the
architecture.

arch_*() functions are meant to be defined by architectures, so revert the
aforementioned commit and re-implement it in a way that keeps
arch_set_thermal_pressure() architecture-definable, and doesn't define the
thermal pressure percpu variable for kernels that don't need
it (CONFIG_SCHED_THERMAL_PRESSURE=n).

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200712165917.9168-2-valentin.schneider@arm.com
2020-07-22 10:22:05 +02:00
Valentin Schneider
36c5bdc438 sched/topology: Kill SD_LOAD_BALANCE
That flag is set unconditionally in sd_init(), and no one checks for it
anymore. Remove it.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200415210512.805-5-valentin.schneider@arm.com
2020-04-30 20:14:39 +02:00
Gustavo A. R. Silva
fe946db6ca sched: topology.h: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2020-04-18 15:44:56 -05:00
Thara Gopinath
36a0df85d2 sched/topology: Add callback to read per CPU thermal pressure
Introduce the arch_scale_thermal_pressure() callback to retrieve per CPU thermal
pressure.

Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200222005213.3873-3-thara.gopinath@linaro.org
2020-03-06 12:57:17 +01:00
Mathieu Poirier
c22645f4c8 sched/topology: Add partition_sched_domains_locked()
Introduce the partition_sched_domains_locked() function by taking
the mutex locking code out of the original function.  That way
the work done by partition_sched_domains_locked() can be reused
without dropping the mutex lock.

No change of functionality is introduced by this patch.

Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bristot@redhat.com
Cc: claudio@evidence.eu.com
Cc: lizefan@huawei.com
Cc: longman@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: rostedt@goodmis.org
Cc: tommaso.cucinotta@santannapisa.it
Link: https://lkml.kernel.org/r/20190719140000.31694-2-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-07-25 15:51:57 +02:00
Patrick Bellasi
69842cba9a sched/uclamp: Add CPU's clamp buckets refcounting
Utilization clamping allows to clamp the CPU's utilization within a
[util_min, util_max] range, depending on the set of RUNNABLE tasks on
that CPU. Each task references two "clamp buckets" defining its minimum
and maximum (util_{min,max}) utilization "clamp values". A CPU's clamp
bucket is active if there is at least one RUNNABLE tasks enqueued on
that CPU and refcounting that bucket.

When a task is {en,de}queued {on,from} a rq, the set of active clamp
buckets on that CPU can change. If the set of active clamp buckets
changes for a CPU a new "aggregated" clamp value is computed for that
CPU. This is because each clamp bucket enforces a different utilization
clamp value.

Clamp values are always MAX aggregated for both util_min and util_max.
This ensures that no task can affect the performance of other
co-scheduled tasks which are more boosted (i.e. with higher util_min
clamp) or less capped (i.e. with higher util_max clamp).

A task has:
   task_struct::uclamp[clamp_id]::bucket_id
to track the "bucket index" of the CPU's clamp bucket it refcounts while
enqueued, for each clamp index (clamp_id).

A runqueue has:
   rq::uclamp[clamp_id]::bucket[bucket_id].tasks
to track how many RUNNABLE tasks on that CPU refcount each
clamp bucket (bucket_id) of a clamp index (clamp_id).
It also has a:
   rq::uclamp[clamp_id]::bucket[bucket_id].value
to track the clamp value of each clamp bucket (bucket_id) of a clamp
index (clamp_id).

The rq::uclamp::bucket[clamp_id][] array is scanned every time it's
needed to find a new MAX aggregated clamp value for a clamp_id. This
operation is required only when it's dequeued the last task of a clamp
bucket tracking the current MAX aggregated clamp value. In this case,
the CPU is either entering IDLE or going to schedule a less boosted or
more clamped task.
The expected number of different clamp values configured at build time
is small enough to fit the full unordered array into a single cache
line, for configurations of up to 7 buckets.

Add to struct rq the basic data structures required to refcount the
number of RUNNABLE tasks for each clamp bucket. Add also the max
aggregation required to update the rq's clamp value at each
enqueue/dequeue event.

Use a simple linear mapping of clamp values into clamp buckets.
Pre-compute and cache bucket_id to avoid integer divisions at
enqueue/dequeue time.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-2-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-06-24 19:23:44 +02:00
Vincent Guittot
8ec59c0f5f sched/topology: Remove unused 'sd' parameter from arch_scale_cpu_capacity()
The 'struct sched_domain *sd' parameter to arch_scale_cpu_capacity() is
unused since commit:

  765d0af19f ("sched/topology: Remove the ::smt_gain field from 'struct sched_domain'")

Remove it.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: gregkh@linuxfoundation.org
Cc: linux@armlinux.org.uk
Cc: quentin.perret@arm.com
Cc: rafael@kernel.org
Link: https://lkml.kernel.org/r/1560783617-5827-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-06-24 19:23:39 +02:00
Dietmar Eggemann
0e1fef63d9 sched/core: Remove sd->*_idx
The sched domain per rq load index files also disappear from the
/proc/sys/kernel/sched_domain/cpuX/domainY directories.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20190527062116.11512-6-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-06-03 11:49:40 +02:00
Joel Fernandes (Google)
994aeb7a93 sched_domain: Annotate RCU pointers properly
The scheduler uses RCU API in various places to access sched_domain
pointers. These cause sparse errors as below.

Many new errors show up because of an annotation check I added to
rcu_assign_pointer(). Let us annotate the pointers correctly which also
will help sparse catch any potential future bugs.

This fixes the following sparse errors:

  rt.c:1681:9: error: incompatible types in comparison expression
  deadline.c:1904:9: error: incompatible types in comparison expression
  core.c:519:9: error: incompatible types in comparison expression
  core.c:1634:17: error: incompatible types in comparison expression
  fair.c:6193:14: error: incompatible types in comparison expression
  fair.c:9883:22: error: incompatible types in comparison expression
  fair.c:9897:9: error: incompatible types in comparison expression
  sched.h:1287:9: error: incompatible types in comparison expression
  topology.c:612:9: error: incompatible types in comparison expression
  topology.c:615:9: error: incompatible types in comparison expression
  sched.h:1300:9: error: incompatible types in comparison expression
  topology.c:618:9: error: incompatible types in comparison expression
  sched.h:1287:9: error: incompatible types in comparison expression
  topology.c:621:9: error: incompatible types in comparison expression
  sched.h:1300:9: error: incompatible types in comparison expression
  topology.c:624:9: error: incompatible types in comparison expression
  topology.c:671:9: error: incompatible types in comparison expression
  stats.c:45:17: error: incompatible types in comparison expression
  fair.c:5998:15: error: incompatible types in comparison expression
  fair.c:5989:15: error: incompatible types in comparison expression
  fair.c:5998:15: error: incompatible types in comparison expression
  fair.c:5989:15: error: incompatible types in comparison expression
  fair.c:6120:19: error: incompatible types in comparison expression
  fair.c:6506:14: error: incompatible types in comparison expression
  fair.c:6515:14: error: incompatible types in comparison expression
  fair.c:6623:9: error: incompatible types in comparison expression
  fair.c:5970:17: error: incompatible types in comparison expression
  fair.c:8642:21: error: incompatible types in comparison expression
  fair.c:9253:9: error: incompatible types in comparison expression
  fair.c:9331:9: error: incompatible types in comparison expression
  fair.c:9519:15: error: incompatible types in comparison expression
  fair.c:9533:14: error: incompatible types in comparison expression
  fair.c:9542:14: error: incompatible types in comparison expression
  fair.c:9567:14: error: incompatible types in comparison expression
  fair.c:9597:14: error: incompatible types in comparison expression
  fair.c:9421:16: error: incompatible types in comparison expression
  fair.c:9421:16: error: incompatible types in comparison expression

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[ From an RCU perspective. ]
Reviewed-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Cc: kernel-hardening@lists.openwall.com
Cc: kernel-team@android.com
Link: https://lkml.kernel.org/r/20190321003426.160260-3-joel@joelfernandes.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-03 12:34:31 +02:00
Luc Van Oostenryck
99687cdbb3 sched/topology: Fix percpu data types in struct sd_data & struct s_data
The percpu members of struct sd_data and s_data are declared as:

	struct ... ** __percpu member;

So their type is:

	__percpu pointer to pointer to struct ...

But looking at how they're used, their type should be:

	pointer to __percpu pointer to struct ...

and they should thus be declared as:

	struct ... * __percpu *member;

So fix the placement of '__percpu' in the definition of these
structures.

This addresses a bunch of Sparse's warnings like:

	warning: incorrect type in initializer (different address spaces)
	  expected void const [noderef] <asn:3> *__vpp_verify
	  got struct sched_domain **

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190118144936.79158-1-luc.vanoostenryck@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-11 08:02:15 +01:00
Quentin Perret
5bd0988be1 sched/topology: Relocate arch_scale_cpu_capacity() to the internal header
By default, arch_scale_cpu_capacity() is only visible from within the
kernel/sched folder. Relocate it to include/linux/sched/topology.h to
make it visible to other clients needing to know about the capacity of
CPUs, such as the Energy Model framework.

This also shrinks the <linux/sched/topology.h> public header.

Signed-off-by: Quentin Perret <quentin.perret@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: adharmap@codeaurora.org
Cc: chris.redpath@arm.com
Cc: currojerez@riseup.net
Cc: dietmar.eggemann@arm.com
Cc: edubezval@gmail.com
Cc: gregkh@linuxfoundation.org
Cc: javi.merino@kernel.org
Cc: joel@joelfernandes.org
Cc: juri.lelli@redhat.com
Cc: morten.rasmussen@arm.com
Cc: patrick.bellasi@arm.com
Cc: pkondeti@codeaurora.org
Cc: rjw@rjwysocki.net
Cc: skannan@codeaurora.org
Cc: smuckle@google.com
Cc: srinivas.pandruvada@linux.intel.com
Cc: thara.gopinath@linaro.org
Cc: tkjos@google.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Cc: viresh.kumar@linaro.org
Link: https://lkml.kernel.org/r/20181203095628.11858-2-quentin.perret@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-12-11 15:16:58 +01:00
Vincent Guittot
765d0af19f sched/topology: Remove the ::smt_gain field from 'struct sched_domain'
::smt_gain is used to compute the capacity of CPUs of a SMT core with the
constraint 1 < ::smt_gain < 2 in order to be able to compute number of CPUs
per core. The field has_free_capacity of struct numa_stat, which was the
last user of this computation of number of CPUs per core, has been removed
by:

  2d4056fafa ("sched/numa: Remove numa_has_capacity()")

We can now remove this constraint on core capacity and use the defautl value
SCHED_CAPACITY_SCALE for SMT CPUs. With this remove, SCHED_CAPACITY_SCALE
becomes the maximum compute capacity of CPUs on every systems. This should
help to simplify some code and remove fields like rd->max_cpu_capacity

Furthermore, arch_scale_cpu_capacity() is used with a NULL sd in several other
places in the code when it wants the capacity of a CPUs to scale
some metrics like in pelt, deadline or schedutil. In case on SMT, the value
returned is not the capacity of SMT CPUs but default SCHED_CAPACITY_SCALE.

So remove it.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1535548752-4434-4-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-12-11 15:16:57 +01:00
Morten Rasmussen
05484e0984 sched/topology: Add SD_ASYM_CPUCAPACITY flag detection
The SD_ASYM_CPUCAPACITY sched_domain flag is supposed to mark the
sched_domain in the hierarchy where all CPU capacities are visible for
any CPU's point of view on asymmetric CPU capacity systems. The
scheduler can then take to take capacity asymmetry into account when
balancing at this level. It also serves as an indicator for how wide
task placement heuristics have to search to consider all available CPU
capacities as asymmetric systems might often appear symmetric at
smallest level(s) of the sched_domain hierarchy.

The flag has been around for while but so far only been set by
out-of-tree code in Android kernels. One solution is to let each
architecture provide the flag through a custom sched_domain topology
array and associated mask and flag functions. However,
SD_ASYM_CPUCAPACITY is special in the sense that it depends on the
capacity and presence of all CPUs in the system, i.e. when hotplugging
all CPUs out except those with one particular CPU capacity the flag
should disappear even if the sched_domains don't collapse. Similarly,
the flag is affected by cpusets where load-balancing is turned off.
Detecting when the flags should be set therefore depends not only on
topology information but also the cpuset configuration and hotplug
state. The arch code doesn't have easy access to the cpuset
configuration.

Instead, this patch implements the flag detection in generic code where
cpusets and hotplug state is already taken care of. All the arch is
responsible for is to implement arch_scale_cpu_capacity() and force a
full rebuild of the sched_domain hierarchy if capacities are updated,
e.g. later in the boot process when cpufreq has initialized.

Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1532093554-30504-2-git-send-email-morten.rasmussen@arm.com
[ Fixed 'CPU' capitalization. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-09-10 11:05:45 +02:00
Juri Lelli
7e1a9208f6 sched/cpufreq: Move arch_scale_{freq,cpu}_capacity() outside of #ifdef CONFIG_SMP
Currently, frequency and cpu capacity scaling is only performed on
CONFIG_SMP systems (as CFS PELT signals are only present for such
systems). However, other scheduling classes want to do freq/cpu scaling,
and for !CONFIG_SMP configurations as well.

arch_scale_freq_capacity() is useful to implement frequency scaling even
on !CONFIG_SMP platforms, so we simply move it outside CONFIG_SMP
ifdeffery.

Even if arch_scale_cpu_capacity() is not useful on !CONFIG_SMP platforms,
we make a default implementation available for such configurations anyway
to simplify scheduler code doing CPU scale invariance.

Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: alessio.balsini@arm.com
Cc: bristot@redhat.com
Cc: claudio@evidence.eu.com
Cc: dietmar.eggemann@arm.com
Cc: joelaf@google.com
Cc: juri.lelli@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: mathieu.poirier@linaro.org
Cc: morten.rasmussen@arm.com
Cc: patrick.bellasi@arm.com
Cc: rjw@rjwysocki.net
Cc: tkjos@android.com
Cc: tommaso.cucinotta@santannapisa.it
Cc: vincent.guittot@linaro.org
Cc: viresh.kumar@linaro.org
Link: http://lkml.kernel.org/r/20171204102325.5110-8-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-01-10 12:53:35 +01:00
Greg Kroah-Hartman
b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00
Peter Zijlstra
d153b15344 sched/core: Fix wake_affine() performance regression
Eric reported a sysbench regression against commit:

  3fed382b46 ("sched/numa: Implement NUMA node level wake_affine()")

Similarly, Rik was looking at the NAS-lu.C benchmark, which regressed
against his v3.10 enterprise kernel.

PRE (current tip/master):

 ivb-ep sysbench:

   2: [30 secs]     transactions:                        64110  (2136.94 per sec.)
   5: [30 secs]     transactions:                        143644 (4787.99 per sec.)
  10: [30 secs]     transactions:                        274298 (9142.93 per sec.)
  20: [30 secs]     transactions:                        418683 (13955.45 per sec.)
  40: [30 secs]     transactions:                        320731 (10690.15 per sec.)
  80: [30 secs]     transactions:                        355096 (11834.28 per sec.)

 hsw-ex NAS:

 OMP_PROC_BIND/lu.C.x_threads_144_run_1.log: Time in seconds =                    18.01
 OMP_PROC_BIND/lu.C.x_threads_144_run_2.log: Time in seconds =                    17.89
 OMP_PROC_BIND/lu.C.x_threads_144_run_3.log: Time in seconds =                    17.93
 lu.C.x_threads_144_run_1.log: Time in seconds =                   434.68
 lu.C.x_threads_144_run_2.log: Time in seconds =                   405.36
 lu.C.x_threads_144_run_3.log: Time in seconds =                   433.83

POST (+patch):

 ivb-ep sysbench:

   2: [30 secs]     transactions:                        64494  (2149.75 per sec.)
   5: [30 secs]     transactions:                        145114 (4836.99 per sec.)
  10: [30 secs]     transactions:                        278311 (9276.69 per sec.)
  20: [30 secs]     transactions:                        437169 (14571.60 per sec.)
  40: [30 secs]     transactions:                        669837 (22326.73 per sec.)
  80: [30 secs]     transactions:                        631739 (21055.88 per sec.)

 hsw-ex NAS:

 lu.C.x_threads_144_run_1.log: Time in seconds =                    23.36
 lu.C.x_threads_144_run_2.log: Time in seconds =                    22.96
 lu.C.x_threads_144_run_3.log: Time in seconds =                    22.52

This patch takes out all the shiny wake_affine() stuff and goes back to
utter basics. Between the two CPUs involved with the wakeup (the CPU
doing the wakeup and the CPU we ran on previously) pick the CPU we can
run on _now_.

This restores much of the regressions against the older kernels,
but leaves some ground in the overloaded case. The default-enabled
WA_WEIGHT (which will be introduced in the next patch) is an attempt
to address the overloaded situation.

Reported-by: Eric Farman <farman@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Rosato <mjrosato@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: jinpuwang@gmail.com
Cc: vcaputo@pengaru.com
Fixes: 3fed382b46 ("sched/numa: Implement NUMA node level wake_affine()")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-10 10:14:02 +02:00
Peter Zijlstra
90001d67be sched/fair: Fix wake_affine() for !NUMA_BALANCING
In commit:

  3fed382b46 ("sched/numa: Implement NUMA node level wake_affine()")

Rik changed wake_affine to consider NUMA information when balancing
between LLC domains.

There are a number of problems here which this patch tries to address:

 - LLC < NODE; in this case we'd use the wrong information to balance
 - !NUMA_BALANCING: in this case, the new code doesn't do any
   balancing at all
 - re-computes the NUMA data for every wakeup, this can mean iterating
   up to 64 CPUs for every wakeup.
 - default affine wakeups inside a cache

We address these by saving the load/capacity values for each
sched_domain during regular load-balance and using these values in
wake_affine_llc(). The obvious down-side to using cached values is
that they can be too old and poorly reflect reality.

But this way we can use LLC wide information and thus not rely on
assuming LLC matches NODE. We also don't rely on NUMA_BALANCING nor do
we have to aggegate two nodes (or even cache domains) worth of CPUs
for each wakeup.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Fixes: 3fed382b46 ("sched/numa: Implement NUMA node level wake_affine()")
[ Minor readability improvements. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10 13:25:14 +02:00
Ingo Molnar
ee6a3d19f1 sched/headers: Remove the <linux/topology.h> include from <linux/sched.h>
It's used only by a single (rarely used) inline function (task_node(p)),
which we can move to <linux/sched/topology.h>.

( Add <linux/nodemask.h>, because we rely on that. )

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-03 01:45:41 +01:00
Ingo Molnar
c03cb28e7c sched/headers: Remove <linux/sched.h> from <linux/sched/topology.h>
The <linux/sched/topology.h> file is a self-contained header and users of
it either don't need <linux/sched.h> - or have already included it.

This reduces the size of the header dependency graph.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-03 01:45:27 +01:00
Ingo Molnar
a60b9eda67 sched/headers: Move scheduler topology interfaces to <linux/sched/topology.h>
The vast majority of sched.h users does not require the topology types and
interfaces, so split them out into <linux/sched/topology.h>.

This reduces the size of linux/sched.h by ~6%.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:42:41 +01:00
Ingo Molnar
4c822698cb sched/headers: Prepare for new header dependencies before moving code to <linux/sched/idle.h>
We are going to split  <linux/sched/idle.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/idle.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:42:26 +01:00
Ingo Molnar
105ab3d8ce sched/headers: Prepare for new header dependencies before moving code to <linux/sched/topology.h>
We are going to split <linux/sched/topology.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/topology.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:42:26 +01:00