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Martin Schwidefsky
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RAID/s390: provide raid6 recovery optimization
The XC instruction can be used to improve the speed of the raid6 recovery. The loops now operate on blocks of 256 bytes. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
1 parent 7bac4f5 commit f5b55fa

4 files changed

Lines changed: 121 additions & 1 deletion

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‎include/linux/raid/pq.h‎

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@@ -116,6 +116,7 @@ struct raid6_recov_calls {
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extern const struct raid6_recov_calls raid6_recov_intx1;
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extern const struct raid6_recov_calls raid6_recov_ssse3;
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extern const struct raid6_recov_calls raid6_recov_avx2;
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extern const struct raid6_recov_calls raid6_recov_s390xc;
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extern const struct raid6_calls raid6_neonx1;
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extern const struct raid6_calls raid6_neonx2;

‎lib/raid6/Makefile‎

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@@ -7,7 +7,7 @@ raid6_pq-$(CONFIG_X86) += recov_ssse3.o recov_avx2.o mmx.o sse1.o sse2.o avx2.o
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raid6_pq-$(CONFIG_ALTIVEC) += altivec1.o altivec2.o altivec4.o altivec8.o
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raid6_pq-$(CONFIG_KERNEL_MODE_NEON) += neon.o neon1.o neon2.o neon4.o neon8.o
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raid6_pq-$(CONFIG_TILEGX) += tilegx8.o
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raid6_pq-$(CONFIG_S390) += s390vx8.o
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raid6_pq-$(CONFIG_S390) += s390vx8.o recov_s390xc.o
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hostprogs-y += mktables
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‎lib/raid6/algos.c‎

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@@ -97,6 +97,9 @@ const struct raid6_recov_calls *const raid6_recov_algos[] = {
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#endif
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#ifdef CONFIG_AS_SSSE3
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&raid6_recov_ssse3,
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#endif
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#ifdef CONFIG_S390
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&raid6_recov_s390xc,
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#endif
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&raid6_recov_intx1,
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NULL

‎lib/raid6/recov_s390xc.c‎

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@@ -0,0 +1,116 @@
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/*
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* RAID-6 data recovery in dual failure mode based on the XC instruction.
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*
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* Copyright IBM Corp. 2016
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* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
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*/
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#include <linux/export.h>
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#include <linux/raid/pq.h>
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static inline void xor_block(u8 *p1, u8 *p2)
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{
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typedef struct { u8 _[256]; } addrtype;
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asm volatile(
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" xc 0(256,%[p1]),0(%[p2])\n"
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: "+m" (*(addrtype *) p1) : "m" (*(addrtype *) p2),
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[p1] "a" (p1), [p2] "a" (p2) : "cc");
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}
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/* Recover two failed data blocks. */
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static void raid6_2data_recov_s390xc(int disks, size_t bytes, int faila,
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int failb, void **ptrs)
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{
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u8 *p, *q, *dp, *dq;
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const u8 *pbmul; /* P multiplier table for B data */
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const u8 *qmul; /* Q multiplier table (for both) */
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int i;
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p = (u8 *)ptrs[disks-2];
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q = (u8 *)ptrs[disks-1];
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/* Compute syndrome with zero for the missing data pages
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Use the dead data pages as temporary storage for
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delta p and delta q */
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dp = (u8 *)ptrs[faila];
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ptrs[faila] = (void *)raid6_empty_zero_page;
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ptrs[disks-2] = dp;
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dq = (u8 *)ptrs[failb];
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ptrs[failb] = (void *)raid6_empty_zero_page;
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ptrs[disks-1] = dq;
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raid6_call.gen_syndrome(disks, bytes, ptrs);
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/* Restore pointer table */
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ptrs[faila] = dp;
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ptrs[failb] = dq;
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ptrs[disks-2] = p;
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ptrs[disks-1] = q;
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/* Now, pick the proper data tables */
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pbmul = raid6_gfmul[raid6_gfexi[failb-faila]];
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qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]];
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/* Now do it... */
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while (bytes) {
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xor_block(dp, p);
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xor_block(dq, q);
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for (i = 0; i < 256; i++)
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dq[i] = pbmul[dp[i]] ^ qmul[dq[i]];
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xor_block(dp, dq);
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p += 256;
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q += 256;
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dp += 256;
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dq += 256;
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bytes -= 256;
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}
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}
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/* Recover failure of one data block plus the P block */
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static void raid6_datap_recov_s390xc(int disks, size_t bytes, int faila,
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void **ptrs)
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{
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u8 *p, *q, *dq;
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const u8 *qmul; /* Q multiplier table */
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int i;
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p = (u8 *)ptrs[disks-2];
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q = (u8 *)ptrs[disks-1];
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/* Compute syndrome with zero for the missing data page
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Use the dead data page as temporary storage for delta q */
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dq = (u8 *)ptrs[faila];
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ptrs[faila] = (void *)raid6_empty_zero_page;
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ptrs[disks-1] = dq;
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raid6_call.gen_syndrome(disks, bytes, ptrs);
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/* Restore pointer table */
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ptrs[faila] = dq;
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ptrs[disks-1] = q;
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/* Now, pick the proper data tables */
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qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]]];
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/* Now do it... */
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while (bytes) {
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xor_block(dq, q);
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for (i = 0; i < 256; i++)
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dq[i] = qmul[dq[i]];
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xor_block(p, dq);
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p += 256;
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q += 256;
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dq += 256;
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bytes -= 256;
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}
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}
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const struct raid6_recov_calls raid6_recov_s390xc = {
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.data2 = raid6_2data_recov_s390xc,
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.datap = raid6_datap_recov_s390xc,
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.valid = NULL,
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.name = "s390xc",
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.priority = 1,
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};

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