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Illumos 5694 - traverse_prefetcher does not prefetch enough 

5694 traverse_prefetcher does not prefetch enough
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Alex Reece <alex@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Josef 'Jeff' Sipek <josef.sipek@nexenta.com>
Reviewed by: Bayard Bell <buffer.g.overflow@gmail.com>
Approved by: Garrett D'Amore <garrett@damore.org>

References:
  https://www.illumos.org/issues/5694
  https://github.com/illumos/illumos-gate/commit/34d7ce05

Ported-by: Chris Dunlop <chris@onthe.net.au>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3230
This commit is contained in:
George Wilson 2015-03-27 15:31:52 +11:00 committed by Brian Behlendorf
parent ee2f17aa2a
commit b738bc5a0f
2 changed files with 13 additions and 14 deletions
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4
man/man5/zfs-module-parameters.5
View File

@ -1058,10 +1058,10 @@ Use \fB1\fR for yes (default) and \fB0\fR to disable.
.sp
.ne 2
.na
\fBzfs_pd_blks_max\fR (int)
\fBzfs_pd_bytes_max\fR (int)
.ad
.RS 12n
Max number of blocks to prefetch
The number of bytes which should be prefetched.
.sp
Default value: \fB100\fR.
.RE

23
module/zfs/dmu_traverse.c
View File

@ -38,13 +38,12 @@
#include <sys/callb.h>
#include <sys/zfeature.h>
int zfs_pd_blks_max = 100;
int32_t zfs_pd_bytes_max = 50 * 1024 * 1024; /* 50MB */
typedef struct prefetch_data {
kmutex_t pd_mtx;
kcondvar_t pd_cv;
int pd_blks_max;
int pd_blks_fetched;
int32_t pd_bytes_fetched;
int pd_flags;
boolean_t pd_cancel;
boolean_t pd_exited;
@ -251,11 +250,12 @@ traverse_visitbp(traverse_data_t *td, const dnode_phys_t *dnp,
}
if (pd != NULL && !pd->pd_exited && prefetch_needed(pd, bp)) {
uint64_t size = BP_GET_LSIZE(bp);
mutex_enter(&pd->pd_mtx);
ASSERT(pd->pd_blks_fetched >= 0);
while (pd->pd_blks_fetched == 0 && !pd->pd_exited)
ASSERT(pd->pd_bytes_fetched >= 0);
while (pd->pd_bytes_fetched < size && !pd->pd_exited)
cv_wait(&pd->pd_cv, &pd->pd_mtx);
pd->pd_blks_fetched--;
pd->pd_bytes_fetched -= size;
cv_broadcast(&pd->pd_cv);
mutex_exit(&pd->pd_mtx);
}
@ -452,7 +452,7 @@ traverse_prefetcher(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
prefetch_data_t *pfd = arg;
uint32_t aflags = ARC_NOWAIT | ARC_PREFETCH;
ASSERT(pfd->pd_blks_fetched >= 0);
ASSERT(pfd->pd_bytes_fetched >= 0);
if (pfd->pd_cancel)
return (SET_ERROR(EINTR));
@ -460,9 +460,9 @@ traverse_prefetcher(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
return (0);
mutex_enter(&pfd->pd_mtx);
while (!pfd->pd_cancel && pfd->pd_blks_fetched >= pfd->pd_blks_max)
while (!pfd->pd_cancel && pfd->pd_bytes_fetched >= zfs_pd_bytes_max)
cv_wait(&pfd->pd_cv, &pfd->pd_mtx);
pfd->pd_blks_fetched++;
pfd->pd_bytes_fetched += BP_GET_LSIZE(bp);
cv_broadcast(&pfd->pd_cv);
mutex_exit(&pfd->pd_mtx);
@ -531,7 +531,6 @@ traverse_impl(spa_t *spa, dsl_dataset_t *ds, uint64_t objset, blkptr_t *rootbp,
td->td_flags = flags;
td->td_paused = B_FALSE;
pd->pd_blks_max = zfs_pd_blks_max;
pd->pd_flags = flags;
mutex_init(&pd->pd_mtx, NULL, MUTEX_DEFAULT, NULL);
cv_init(&pd->pd_cv, NULL, CV_DEFAULT, NULL);
@ -661,6 +660,6 @@ traverse_pool(spa_t *spa, uint64_t txg_start, int flags,
EXPORT_SYMBOL(traverse_dataset);
EXPORT_SYMBOL(traverse_pool);
module_param(zfs_pd_blks_max, int, 0644);
MODULE_PARM_DESC(zfs_pd_blks_max, "Max number of blocks to prefetch");
module_param(zfs_pd_bytes_max, int, 0644);
MODULE_PARM_DESC(zfs_pd_bytes_max, "Max number of bytes to prefetch");
#endif