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bianbu-linux-6.6/lib/raid6/algos.c
WANG Xuerui 8f3f06dfd6 raid6: Add LoongArch SIMD syndrome calculation 
The algorithms work on 64 bytes at a time, which is the L1 cache line
size of all current and future LoongArch cores (that we care about), as
confirmed by Huacai. The code is based on the generic int.uc algorithm,
unrolled 4 times for LSX and 2 times for LASX. Further unrolling does
not meaningfully improve the performance according to experiments.

Performance numbers measured during system boot on a 3A5000 @ 2.5GHz:

> raid6: lasx     gen() 12726 MB/s
> raid6: lsx      gen() 10001 MB/s
> raid6: int64x8  gen()  2876 MB/s
> raid6: int64x4  gen()  3867 MB/s
> raid6: int64x2  gen()  2531 MB/s
> raid6: int64x1  gen()  1945 MB/s

Comparison of xor() speeds (from different boots but meaningful anyway):

> lasx:    11226 MB/s
> lsx:     6395 MB/s
> int64x4: 2147 MB/s

Performance as measured by raid6test:

> raid6: lasx     gen() 25109 MB/s
> raid6: lsx      gen() 13233 MB/s
> raid6: int64x8  gen()  4164 MB/s
> raid6: int64x4  gen()  6005 MB/s
> raid6: int64x2  gen()  5781 MB/s
> raid6: int64x1  gen()  4119 MB/s
> raid6: using algorithm lasx gen() 25109 MB/s
> raid6: .... xor() 14439 MB/s, rmw enabled

Acked-by: Song Liu <song@kernel.org>
Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2023-09-06 22:53:55 +08:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/* -*- linux-c -*- ------------------------------------------------------- *
*
* Copyright 2002 H. Peter Anvin - All Rights Reserved
*
* ----------------------------------------------------------------------- */
/*
* raid6/algos.c
*
* Algorithm list and algorithm selection for RAID-6
*/
#include <linux/raid/pq.h>
#ifndef __KERNEL__
#include <sys/mman.h>
#include <stdio.h>
#else
#include <linux/module.h>
#include <linux/gfp.h>
/* In .bss so it's zeroed */
const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
EXPORT_SYMBOL(raid6_empty_zero_page);
#endif
struct raid6_calls raid6_call;
EXPORT_SYMBOL_GPL(raid6_call);
const struct raid6_calls * const raid6_algos[] = {
#if defined(__i386__) && !defined(__arch_um__)
#ifdef CONFIG_AS_AVX512
&raid6_avx512x2,
&raid6_avx512x1,
#endif
&raid6_avx2x2,
&raid6_avx2x1,
&raid6_sse2x2,
&raid6_sse2x1,
&raid6_sse1x2,
&raid6_sse1x1,
&raid6_mmxx2,
&raid6_mmxx1,
#endif
#if defined(__x86_64__) && !defined(__arch_um__)
#ifdef CONFIG_AS_AVX512
&raid6_avx512x4,
&raid6_avx512x2,
&raid6_avx512x1,
#endif
&raid6_avx2x4,
&raid6_avx2x2,
&raid6_avx2x1,
&raid6_sse2x4,
&raid6_sse2x2,
&raid6_sse2x1,
#endif
#ifdef CONFIG_ALTIVEC
&raid6_vpermxor8,
&raid6_vpermxor4,
&raid6_vpermxor2,
&raid6_vpermxor1,
&raid6_altivec8,
&raid6_altivec4,
&raid6_altivec2,
&raid6_altivec1,
#endif
#if defined(CONFIG_S390)
&raid6_s390vx8,
#endif
#ifdef CONFIG_KERNEL_MODE_NEON
&raid6_neonx8,
&raid6_neonx4,
&raid6_neonx2,
&raid6_neonx1,
#endif
#ifdef CONFIG_LOONGARCH
#ifdef CONFIG_CPU_HAS_LASX
&raid6_lasx,
#endif
#ifdef CONFIG_CPU_HAS_LSX
&raid6_lsx,
#endif
#endif
#if defined(__ia64__)
&raid6_intx32,
&raid6_intx16,
#endif
&raid6_intx8,
&raid6_intx4,
&raid6_intx2,
&raid6_intx1,
NULL
};
void (*raid6_2data_recov)(int, size_t, int, int, void **);
EXPORT_SYMBOL_GPL(raid6_2data_recov);
void (*raid6_datap_recov)(int, size_t, int, void **);
EXPORT_SYMBOL_GPL(raid6_datap_recov);
const struct raid6_recov_calls *const raid6_recov_algos[] = {
#ifdef CONFIG_X86
#ifdef CONFIG_AS_AVX512
&raid6_recov_avx512,
#endif
&raid6_recov_avx2,
&raid6_recov_ssse3,
#endif
#ifdef CONFIG_S390
&raid6_recov_s390xc,
#endif
#if defined(CONFIG_KERNEL_MODE_NEON)
&raid6_recov_neon,
#endif
&raid6_recov_intx1,
NULL
};
#ifdef __KERNEL__
#define RAID6_TIME_JIFFIES_LG2 4
#else
/* Need more time to be stable in userspace */
#define RAID6_TIME_JIFFIES_LG2 9
#define time_before(x, y) ((x) < (y))
#endif
#define RAID6_TEST_DISKS 8
#define RAID6_TEST_DISKS_ORDER 3
static inline const struct raid6_recov_calls *raid6_choose_recov(void)
{
const struct raid6_recov_calls *const *algo;
const struct raid6_recov_calls *best;
for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
if (!best || (*algo)->priority > best->priority)
if (!(*algo)->valid || (*algo)->valid())
best = *algo;
if (best) {
raid6_2data_recov = best->data2;
raid6_datap_recov = best->datap;
pr_info("raid6: using %s recovery algorithm\n", best->name);
} else
pr_err("raid6: Yikes! No recovery algorithm found!\n");
return best;
}
static inline const struct raid6_calls *raid6_choose_gen(
void *(*const dptrs)[RAID6_TEST_DISKS], const int disks)
{
unsigned long perf, bestgenperf, j0, j1;
int start = (disks>>1)-1, stop = disks-3; /* work on the second half of the disks */
const struct raid6_calls *const *algo;
const struct raid6_calls *best;
for (bestgenperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
if (!best || (*algo)->priority >= best->priority) {
if ((*algo)->valid && !(*algo)->valid())
continue;
if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
best = *algo;
break;
}
perf = 0;
preempt_disable();
j0 = jiffies;
while ((j1 = jiffies) == j0)
cpu_relax();
while (time_before(jiffies,
j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
(*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
perf++;
}
preempt_enable();
if (perf > bestgenperf) {
bestgenperf = perf;
best = *algo;
}
pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
(perf * HZ * (disks-2)) >>
(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
}
}
if (!best) {
pr_err("raid6: Yikes! No algorithm found!\n");
goto out;
}
raid6_call = *best;
if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
pr_info("raid6: skipped pq benchmark and selected %s\n",
best->name);
goto out;
}
pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
best->name,
(bestgenperf * HZ * (disks - 2)) >>
(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
if (best->xor_syndrome) {
perf = 0;
preempt_disable();
j0 = jiffies;
while ((j1 = jiffies) == j0)
cpu_relax();
while (time_before(jiffies,
j1 + (1 << RAID6_TIME_JIFFIES_LG2))) {
best->xor_syndrome(disks, start, stop,
PAGE_SIZE, *dptrs);
perf++;
}
preempt_enable();
pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
(perf * HZ * (disks - 2)) >>
(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
}
out:
return best;
}
/* Try to pick the best algorithm */
/* This code uses the gfmul table as convenient data set to abuse */
int __init raid6_select_algo(void)
{
const int disks = RAID6_TEST_DISKS;
const struct raid6_calls *gen_best;
const struct raid6_recov_calls *rec_best;
char *disk_ptr, *p;
void *dptrs[RAID6_TEST_DISKS];
int i, cycle;
/* prepare the buffer and fill it circularly with gfmul table */
disk_ptr = (char *)__get_free_pages(GFP_KERNEL, RAID6_TEST_DISKS_ORDER);
if (!disk_ptr) {
pr_err("raid6: Yikes! No memory available.\n");
return -ENOMEM;
}
p = disk_ptr;
for (i = 0; i < disks; i++)
dptrs[i] = p + PAGE_SIZE * i;
cycle = ((disks - 2) * PAGE_SIZE) / 65536;
for (i = 0; i < cycle; i++) {
memcpy(p, raid6_gfmul, 65536);
p += 65536;
}
if ((disks - 2) * PAGE_SIZE % 65536)
memcpy(p, raid6_gfmul, (disks - 2) * PAGE_SIZE % 65536);
/* select raid gen_syndrome function */
gen_best = raid6_choose_gen(&dptrs, disks);
/* select raid recover functions */
rec_best = raid6_choose_recov();
free_pages((unsigned long)disk_ptr, RAID6_TEST_DISKS_ORDER);
return gen_best && rec_best ? 0 : -EINVAL;
}
static void raid6_exit(void)
{
do { } while (0);
}
subsys_initcall(raid6_select_algo);
module_exit(raid6_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
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