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RAIDZ: Use cache blocking during parity math 

RAIDZ parity is calculated by adding data one column at a time.  It
works OK for small blocks, but for large blocks results of previous
addition may already be evicted from CPU caches to main memory, and
in addition to extra memory write require extra read to get it back.

This patch splits large parity operations into 64KB chunks, that
should in most cases fit into CPU L2 caches from the last decade.
I haven't touched more complicated cases of data reconstruction to
not over complicate the code.  Those should be relatively rare.

My tests on Xeon Gold 6242R CPU with 1MB of L2 cache per core show
up to 10/20% memory traffic reduction when writing to 4-wide RAIDZ/
RAIDZ2 blocks of ~4MB and up.  Older CPUs with 256KB of L2 cache
should see the effect even on smaller blocks.  Wider vdevs may need
bigger blocks to be affected.

Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by:	Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
Closes #15448
This commit is contained in:
Alexander Motin 2023-10-30 17:54:27 -04:00 committed by GitHub
parent c3773de168
commit 05a7348a7e
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 104 additions and 82 deletions
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6
include/sys/abd.h
View File

@ -133,11 +133,11 @@ int abd_cmp_buf_off(abd_t *, const void *, size_t, size_t);
void abd_zero_off(abd_t *, size_t, size_t);
void abd_verify(abd_t *);
void abd_raidz_gen_iterate(abd_t **cabds, abd_t *dabd,
ssize_t csize, ssize_t dsize, const unsigned parity,
void abd_raidz_gen_iterate(abd_t **cabds, abd_t *dabd, size_t off,
size_t csize, size_t dsize, const unsigned parity,
void (*func_raidz_gen)(void **, const void *, size_t, size_t));
void abd_raidz_rec_iterate(abd_t **cabds, abd_t **tabds,
ssize_t tsize, const unsigned parity,
size_t tsize, const unsigned parity,
void (*func_raidz_rec)(void **t, const size_t tsize, void **c,
const unsigned *mul),
const unsigned *mul);

24
module/zfs/abd.c
View File

@ -1017,12 +1017,12 @@ abd_cmp(abd_t *dabd, abd_t *sabd)
* is the same when taking linear and when taking scatter
*/
void
abd_raidz_gen_iterate(abd_t **cabds, abd_t *dabd,
ssize_t csize, ssize_t dsize, const unsigned parity,
abd_raidz_gen_iterate(abd_t **cabds, abd_t *dabd, size_t off,
size_t csize, size_t dsize, const unsigned parity,
void (*func_raidz_gen)(void **, const void *, size_t, size_t))
{
int i;
ssize_t len, dlen;
size_t len, dlen;
struct abd_iter caiters[3];
struct abd_iter daiter;
void *caddrs[3];
@ -1033,16 +1033,15 @@ abd_raidz_gen_iterate(abd_t **cabds, abd_t *dabd,
ASSERT3U(parity, <=, 3);
for (i = 0; i < parity; i++) {
abd_verify(cabds[i]);
ASSERT3U(csize, <=, cabds[i]->abd_size);
c_cabds[i] = abd_init_abd_iter(cabds[i], &caiters[i], 0);
ASSERT3U(off + csize, <=, cabds[i]->abd_size);
c_cabds[i] = abd_init_abd_iter(cabds[i], &caiters[i], off);
}
ASSERT3S(dsize, >=, 0);
if (dsize > 0) {
ASSERT(dabd);
abd_verify(dabd);
ASSERT3U(dsize, <=, dabd->abd_size);
c_dabd = abd_init_abd_iter(dabd, &daiter, 0);
ASSERT3U(off + dsize, <=, dabd->abd_size);
c_dabd = abd_init_abd_iter(dabd, &daiter, off);
}
abd_enter_critical(flags);
@ -1064,7 +1063,7 @@ abd_raidz_gen_iterate(abd_t **cabds, abd_t *dabd,
dlen = 0;
/* must be progressive */
ASSERT3S(len, >, 0);
ASSERT3U(len, >, 0);
/*
* The iterated function likely will not do well if each
* segment except the last one is not multiple of 512 (raidz).
@ -1089,9 +1088,6 @@ abd_raidz_gen_iterate(abd_t **cabds, abd_t *dabd,
}
csize -= len;
ASSERT3S(dsize, >=, 0);
ASSERT3S(csize, >=, 0);
}
abd_exit_critical(flags);
}
@ -1108,13 +1104,13 @@ abd_raidz_gen_iterate(abd_t **cabds, abd_t *dabd,
*/
void
abd_raidz_rec_iterate(abd_t **cabds, abd_t **tabds,
ssize_t tsize, const unsigned parity,
size_t tsize, const unsigned parity,
void (*func_raidz_rec)(void **t, const size_t tsize, void **c,
const unsigned *mul),
const unsigned *mul)
{
int i;
ssize_t len;
size_t len;
struct abd_iter citers[3];
struct abd_iter xiters[3];
void *caddrs[3], *xaddrs[3];

156
module/zfs/vdev_raidz_math_impl.h
View File

@ -214,9 +214,10 @@ raidz_copy_abd_cb(void *dc, void *sc, size_t size, void *private)
}
#define raidz_copy(dabd, sabd, size) \
#define raidz_copy(dabd, sabd, off, size) \
{ \
abd_iterate_func2(dabd, sabd, 0, 0, size, raidz_copy_abd_cb, NULL);\
abd_iterate_func2(dabd, sabd, off, off, size, raidz_copy_abd_cb, \
NULL); \
}
/*
@ -254,9 +255,10 @@ raidz_add_abd_cb(void *dc, void *sc, size_t size, void *private)
return (0);
}
#define raidz_add(dabd, sabd, size) \
#define raidz_add(dabd, sabd, off, size) \
{ \
abd_iterate_func2(dabd, sabd, 0, 0, size, raidz_add_abd_cb, NULL);\
abd_iterate_func2(dabd, sabd, off, off, size, raidz_add_abd_cb, \
NULL); \
}
/*
@ -343,7 +345,10 @@ raidz_mul_abd_cb(void *dc, size_t size, void *private)
* the parity/syndrome if data column is shorter.
*
* P parity is calculated using raidz_add_abd().
*
* For CPU L2 cache blocking we process 64KB at a time.
*/
#define CHUNK 65536
/*
* Generate P parity (RAIDZ1)
@ -357,20 +362,26 @@ raidz_generate_p_impl(raidz_row_t * const rr)
const size_t ncols = rr->rr_cols;
const size_t psize = rr->rr_col[CODE_P].rc_size;
abd_t *pabd = rr->rr_col[CODE_P].rc_abd;
size_t size;
abd_t *dabd;
size_t off, size;
raidz_math_begin();
/* start with first data column */
raidz_copy(pabd, rr->rr_col[1].rc_abd, psize);
for (off = 0; off < psize; off += CHUNK) {
for (c = 2; c < ncols; c++) {
dabd = rr->rr_col[c].rc_abd;
size = rr->rr_col[c].rc_size;
/* start with first data column */
size = MIN(CHUNK, psize - off);
raidz_copy(pabd, rr->rr_col[1].rc_abd, off, size);
/* add data column */
raidz_add(pabd, dabd, size);
for (c = 2; c < ncols; c++) {
size = rr->rr_col[c].rc_size;
if (size <= off)
continue;
/* add data column */
size = MIN(CHUNK, size - off);
abd_t *dabd = rr->rr_col[c].rc_abd;
raidz_add(pabd, dabd, off, size);
}
}
raidz_math_end();
@ -423,7 +434,7 @@ raidz_generate_pq_impl(raidz_row_t * const rr)
size_t c;
const size_t ncols = rr->rr_cols;
const size_t csize = rr->rr_col[CODE_P].rc_size;
size_t dsize;
size_t off, size, dsize;
abd_t *dabd;
abd_t *cabds[] = {
rr->rr_col[CODE_P].rc_abd,
@ -432,15 +443,20 @@ raidz_generate_pq_impl(raidz_row_t * const rr)
raidz_math_begin();
raidz_copy(cabds[CODE_P], rr->rr_col[2].rc_abd, csize);
raidz_copy(cabds[CODE_Q], rr->rr_col[2].rc_abd, csize);
for (off = 0; off < csize; off += CHUNK) {
for (c = 3; c < ncols; c++) {
dabd = rr->rr_col[c].rc_abd;
dsize = rr->rr_col[c].rc_size;
size = MIN(CHUNK, csize - off);
raidz_copy(cabds[CODE_P], rr->rr_col[2].rc_abd, off, size);
raidz_copy(cabds[CODE_Q], rr->rr_col[2].rc_abd, off, size);
abd_raidz_gen_iterate(cabds, dabd, csize, dsize, 2,
raidz_gen_pq_add);
for (c = 3; c < ncols; c++) {
dabd = rr->rr_col[c].rc_abd;
dsize = rr->rr_col[c].rc_size;
dsize = (dsize > off) ? MIN(CHUNK, dsize - off) : 0;
abd_raidz_gen_iterate(cabds, dabd, off, size, dsize, 2,
raidz_gen_pq_add);
}
}
raidz_math_end();
@ -496,7 +512,7 @@ raidz_generate_pqr_impl(raidz_row_t * const rr)
size_t c;
const size_t ncols = rr->rr_cols;
const size_t csize = rr->rr_col[CODE_P].rc_size;
size_t dsize;
size_t off, size, dsize;
abd_t *dabd;
abd_t *cabds[] = {
rr->rr_col[CODE_P].rc_abd,
@ -506,16 +522,21 @@ raidz_generate_pqr_impl(raidz_row_t * const rr)
raidz_math_begin();
raidz_copy(cabds[CODE_P], rr->rr_col[3].rc_abd, csize);
raidz_copy(cabds[CODE_Q], rr->rr_col[3].rc_abd, csize);
raidz_copy(cabds[CODE_R], rr->rr_col[3].rc_abd, csize);
for (off = 0; off < csize; off += CHUNK) {
for (c = 4; c < ncols; c++) {
dabd = rr->rr_col[c].rc_abd;
dsize = rr->rr_col[c].rc_size;
size = MIN(CHUNK, csize - off);
raidz_copy(cabds[CODE_P], rr->rr_col[3].rc_abd, off, size);
raidz_copy(cabds[CODE_Q], rr->rr_col[3].rc_abd, off, size);
raidz_copy(cabds[CODE_R], rr->rr_col[3].rc_abd, off, size);
abd_raidz_gen_iterate(cabds, dabd, csize, dsize, 3,
raidz_gen_pqr_add);
for (c = 4; c < ncols; c++) {
dabd = rr->rr_col[c].rc_abd;
dsize = rr->rr_col[c].rc_size;
dsize = (dsize > off) ? MIN(CHUNK, dsize - off) : 0;
abd_raidz_gen_iterate(cabds, dabd, off, size, dsize, 3,
raidz_gen_pqr_add);
}
}
raidz_math_end();
@ -592,26 +613,31 @@ raidz_reconstruct_p_impl(raidz_row_t *rr, const int *tgtidx)
const size_t x = tgtidx[TARGET_X];
const size_t xsize = rr->rr_col[x].rc_size;
abd_t *xabd = rr->rr_col[x].rc_abd;
size_t size;
abd_t *dabd;
size_t off, size;
if (xabd == NULL)
return (1 << CODE_P);
raidz_math_begin();
/* copy P into target */
raidz_copy(xabd, rr->rr_col[CODE_P].rc_abd, xsize);
for (off = 0; off < xsize; off += CHUNK) {
/* generate p_syndrome */
for (c = firstdc; c < ncols; c++) {
if (c == x)
continue;
/* copy P into target */
size = MIN(CHUNK, xsize - off);
raidz_copy(xabd, rr->rr_col[CODE_P].rc_abd, off, size);
dabd = rr->rr_col[c].rc_abd;
size = MIN(rr->rr_col[c].rc_size, xsize);
/* generate p_syndrome */
for (c = firstdc; c < ncols; c++) {
if (c == x)
continue;
size = rr->rr_col[c].rc_size;
if (size <= off)
continue;
raidz_add(xabd, dabd, size);
size = MIN(CHUNK, MIN(size, xsize) - off);
abd_t *dabd = rr->rr_col[c].rc_abd;
raidz_add(xabd, dabd, off, size);
}
}
raidz_math_end();
@ -683,7 +709,7 @@ raidz_reconstruct_q_impl(raidz_row_t *rr, const int *tgtidx)
/* Start with first data column if present */
if (firstdc != x) {
raidz_copy(xabd, rr->rr_col[firstdc].rc_abd, xsize);
raidz_copy(xabd, rr->rr_col[firstdc].rc_abd, 0, xsize);
} else {
raidz_zero(xabd, xsize);
}
@ -698,12 +724,12 @@ raidz_reconstruct_q_impl(raidz_row_t *rr, const int *tgtidx)
dsize = rr->rr_col[c].rc_size;
}
abd_raidz_gen_iterate(tabds, dabd, xsize, dsize, 1,
abd_raidz_gen_iterate(tabds, dabd, 0, xsize, dsize, 1,
raidz_syn_q_abd);
}
/* add Q to the syndrome */
raidz_add(xabd, rr->rr_col[CODE_Q].rc_abd, xsize);
raidz_add(xabd, rr->rr_col[CODE_Q].rc_abd, 0, xsize);
/* transform the syndrome */
abd_iterate_func(xabd, 0, xsize, raidz_mul_abd_cb, (void*) coeff);
@ -777,7 +803,7 @@ raidz_reconstruct_r_impl(raidz_row_t *rr, const int *tgtidx)
/* Start with first data column if present */
if (firstdc != x) {
raidz_copy(xabd, rr->rr_col[firstdc].rc_abd, xsize);
raidz_copy(xabd, rr->rr_col[firstdc].rc_abd, 0, xsize);
} else {
raidz_zero(xabd, xsize);
}
@ -793,12 +819,12 @@ raidz_reconstruct_r_impl(raidz_row_t *rr, const int *tgtidx)
dsize = rr->rr_col[c].rc_size;
}
abd_raidz_gen_iterate(tabds, dabd, xsize, dsize, 1,
abd_raidz_gen_iterate(tabds, dabd, 0, xsize, dsize, 1,
raidz_syn_r_abd);
}
/* add R to the syndrome */
raidz_add(xabd, rr->rr_col[CODE_R].rc_abd, xsize);
raidz_add(xabd, rr->rr_col[CODE_R].rc_abd, 0, xsize);
/* transform the syndrome */
abd_iterate_func(xabd, 0, xsize, raidz_mul_abd_cb, (void *)coeff);
@ -934,8 +960,8 @@ raidz_reconstruct_pq_impl(raidz_row_t *rr, const int *tgtidx)
/* Start with first data column if present */
if (firstdc != x) {
raidz_copy(xabd, rr->rr_col[firstdc].rc_abd, xsize);
raidz_copy(yabd, rr->rr_col[firstdc].rc_abd, xsize);
raidz_copy(xabd, rr->rr_col[firstdc].rc_abd, 0, xsize);
raidz_copy(yabd, rr->rr_col[firstdc].rc_abd, 0, xsize);
} else {
raidz_zero(xabd, xsize);
raidz_zero(yabd, xsize);
@ -951,7 +977,7 @@ raidz_reconstruct_pq_impl(raidz_row_t *rr, const int *tgtidx)
dsize = rr->rr_col[c].rc_size;
}
abd_raidz_gen_iterate(tabds, dabd, xsize, dsize, 2,
abd_raidz_gen_iterate(tabds, dabd, 0, xsize, dsize, 2,
raidz_syn_pq_abd);
}
@ -959,7 +985,7 @@ raidz_reconstruct_pq_impl(raidz_row_t *rr, const int *tgtidx)
/* Copy shorter targets back to the original abd buffer */
if (ysize < xsize)
raidz_copy(rr->rr_col[y].rc_abd, yabd, ysize);
raidz_copy(rr->rr_col[y].rc_abd, yabd, 0, ysize);
raidz_math_end();
@ -1094,8 +1120,8 @@ raidz_reconstruct_pr_impl(raidz_row_t *rr, const int *tgtidx)
/* Start with first data column if present */
if (firstdc != x) {
raidz_copy(xabd, rr->rr_col[firstdc].rc_abd, xsize);
raidz_copy(yabd, rr->rr_col[firstdc].rc_abd, xsize);
raidz_copy(xabd, rr->rr_col[firstdc].rc_abd, 0, xsize);
raidz_copy(yabd, rr->rr_col[firstdc].rc_abd, 0, xsize);
} else {
raidz_zero(xabd, xsize);
raidz_zero(yabd, xsize);
@ -1111,7 +1137,7 @@ raidz_reconstruct_pr_impl(raidz_row_t *rr, const int *tgtidx)
dsize = rr->rr_col[c].rc_size;
}
abd_raidz_gen_iterate(tabds, dabd, xsize, dsize, 2,
abd_raidz_gen_iterate(tabds, dabd, 0, xsize, dsize, 2,
raidz_syn_pr_abd);
}
@ -1121,7 +1147,7 @@ raidz_reconstruct_pr_impl(raidz_row_t *rr, const int *tgtidx)
* Copy shorter targets back to the original abd buffer
*/
if (ysize < xsize)
raidz_copy(rr->rr_col[y].rc_abd, yabd, ysize);
raidz_copy(rr->rr_col[y].rc_abd, yabd, 0, ysize);
raidz_math_end();
@ -1261,8 +1287,8 @@ raidz_reconstruct_qr_impl(raidz_row_t *rr, const int *tgtidx)
/* Start with first data column if present */
if (firstdc != x) {
raidz_copy(xabd, rr->rr_col[firstdc].rc_abd, xsize);
raidz_copy(yabd, rr->rr_col[firstdc].rc_abd, xsize);
raidz_copy(xabd, rr->rr_col[firstdc].rc_abd, 0, xsize);
raidz_copy(yabd, rr->rr_col[firstdc].rc_abd, 0, xsize);
} else {
raidz_zero(xabd, xsize);
raidz_zero(yabd, xsize);
@ -1278,7 +1304,7 @@ raidz_reconstruct_qr_impl(raidz_row_t *rr, const int *tgtidx)
dsize = rr->rr_col[c].rc_size;
}
abd_raidz_gen_iterate(tabds, dabd, xsize, dsize, 2,
abd_raidz_gen_iterate(tabds, dabd, 0, xsize, dsize, 2,
raidz_syn_qr_abd);
}
@ -1288,7 +1314,7 @@ raidz_reconstruct_qr_impl(raidz_row_t *rr, const int *tgtidx)
* Copy shorter targets back to the original abd buffer
*/
if (ysize < xsize)
raidz_copy(rr->rr_col[y].rc_abd, yabd, ysize);
raidz_copy(rr->rr_col[y].rc_abd, yabd, 0, ysize);
raidz_math_end();
@ -1456,9 +1482,9 @@ raidz_reconstruct_pqr_impl(raidz_row_t *rr, const int *tgtidx)
/* Start with first data column if present */
if (firstdc != x) {
raidz_copy(xabd, rr->rr_col[firstdc].rc_abd, xsize);
raidz_copy(yabd, rr->rr_col[firstdc].rc_abd, xsize);
raidz_copy(zabd, rr->rr_col[firstdc].rc_abd, xsize);
raidz_copy(xabd, rr->rr_col[firstdc].rc_abd, 0, xsize);
raidz_copy(yabd, rr->rr_col[firstdc].rc_abd, 0, xsize);
raidz_copy(zabd, rr->rr_col[firstdc].rc_abd, 0, xsize);
} else {
raidz_zero(xabd, xsize);
raidz_zero(yabd, xsize);
@ -1475,7 +1501,7 @@ raidz_reconstruct_pqr_impl(raidz_row_t *rr, const int *tgtidx)
dsize = rr->rr_col[c].rc_size;
}
abd_raidz_gen_iterate(tabds, dabd, xsize, dsize, 3,
abd_raidz_gen_iterate(tabds, dabd, 0, xsize, dsize, 3,
raidz_syn_pqr_abd);
}
@ -1485,9 +1511,9 @@ raidz_reconstruct_pqr_impl(raidz_row_t *rr, const int *tgtidx)
* Copy shorter targets back to the original abd buffer
*/
if (ysize < xsize)
raidz_copy(rr->rr_col[y].rc_abd, yabd, ysize);
raidz_copy(rr->rr_col[y].rc_abd, yabd, 0, ysize);
if (zsize < xsize)
raidz_copy(rr->rr_col[z].rc_abd, zabd, zsize);
raidz_copy(rr->rr_col[z].rc_abd, zabd, 0, zsize);
raidz_math_end();