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perf core: Per event callchain limit

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Additionally to being able to control the system wide maximum depth via
/proc/sys/kernel/perf_event_max_stack, now we are able to ask for
different depths per event, using perf_event_attr.sample_max_stack for
that.

This uses an u16 hole at the end of perf_event_attr, that, when
perf_event_attr.sample_type has the PERF_SAMPLE_CALLCHAIN, if
sample_max_stack is zero, means use perf_event_max_stack, otherwise
it'll be bounds checked under callchain_mutex.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: Zefan Li <lizefan@huawei.com>
Link: http://lkml.kernel.org/n/tip-kolmn1yo40p7jhswxwrc7rrd@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo 2016-04-28 13:16:33 -03:00
parent 480ca357fd
commit 97c79a38cd
5 changed files with 23 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

6
include/uapi/linux/perf_event.h
View file

@ -276,6 +276,9 @@ enum perf_event_read_format {
/*
* Hardware event_id to monitor via a performance monitoring event:
*
* @sample_max_stack: Max number of frame pointers in a callchain,
* should be < /proc/sys/kernel/perf_event_max_stack
*/
struct perf_event_attr {
@ -385,7 +388,8 @@ struct perf_event_attr {
* Wakeup watermark for AUX area
*/
__u32 aux_watermark;
__u32 __reserved_2; /* align to __u64 */
__u16 sample_max_stack;
__u16 __reserved_2; /* align to __u64 */
};
#define perf_flags(attr) (*(&(attr)->read_format + 1))