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Add dedicated XOR-only fast path for AVX512 rec1of1

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This commit is contained in:
Andrea Mazzoleni 2026-08-31 10:25:20 +02:00
parent e39c21a4c5
commit 5acd43c9e5
1 changed files with 64 additions and 4 deletions
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68
raid/avx512.c
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@ -889,6 +889,62 @@ static __always_inline void raid_recX_avx512bw(int nr, int has_p, int *id, int *
raid_avx_end();
}
/*
* Recover one data failure using P with AVX512BW.
*
* The missing block is:
*
* Dx = P ^ D0 ^ ... ^ D(x-1) ^ D(x+1) ^ ... ^ Dn
*
* Process two surviving data blocks per iteration using vpternlogq.
*/
static __always_inline void raid_rec1of1_avx512bw(int *id, int nd, size_t size, void **vv)
{
uint8_t **v = (uint8_t **)vv;
uint8_t *src[RAID_DATA_MAX];
uint8_t *p;
uint8_t *pa;
size_t i;
int d, s, ns;
p = v[nd];
pa = v[id[0]];
/* build the compact list of surviving data blocks */
ns = 0;
for (d = 0; d < nd; ++d) {
if (d != id[0])
src[ns++] = v[d];
}
BUG_ON(ns != nd - 1);
raid_avx_begin();
for (i = 0; i < size; i += 64) {
/* start from the stored P block */
asm volatile ("vmovdqa64 %0,%%zmm0" : : "m" (p[i]));
/* XOR two surviving data blocks at a time */
for (s = 0; s <= ns - 2; s += 2) {
asm volatile (
"vmovdqa64 %0,%%zmm1\n\t"
"vpternlogq $0x96,%1,%%zmm1,%%zmm0"
:
: "m" (src[s][i]), "m" (src[s + 1][i])
);
}
/* remaining odd survivor */
if (s < ns)
asm volatile ("vpxorq %0,%%zmm0,%%zmm0" : : "m" (src[s][i]));
asm volatile ("vmovdqa64 %%zmm0,%0" : "=m" (pa[i]));
}
raid_avx_end();
}
void raid_gen4_avx512bw(int nd, size_t size, void **vv)
{
raid_genX_avx512bw(nd, size, vv, 4);
@ -907,10 +963,14 @@ void raid_gen6_avx512bw(int nd, size_t size, void **vv)
void raid_rec1_avx512bw(int nr, int *id, int *ip, int nd, size_t size, void **vv)
{
BUG_ON(nr != 1);
if (ip[0] == 0)
raid_recX_avx512bw(1, 1, id, ip, nd, size, vv);
else
raid_recX_avx512bw(1, 0, id, ip, nd, size, vv);
/* if recovering with P, use a custom XOR-only path with temporal stores */
if (ip[0] == 0) {
raid_rec1of1_avx512bw(id, nd, size, vv);
return;
}
raid_recX_avx512bw(1, 0, id, ip, nd, size, vv);
}
void raid_rec2_avx512bw(int nr, int *id, int *ip, int nd, size_t size, void **vv)