diff options
| author | Tom Caputi <[email protected]> | 2017-12-21 12:13:06 -0500 |
|---|---|---|
| committer | Brian Behlendorf <[email protected]> | 2017-12-21 09:13:06 -0800 |
| commit | a8b2e30685c9214ccfd0181977540e080340df4e (patch) | |
| tree | db07450d097c27b1e3d627f8ae58387cad9d0038 /module/zfs/dsl_scan.c | |
| parent | 993669a7bf17a26843630c547999be0b27483497 (diff) | |
Support re-prioritizing asynchronous prefetches
When sequential scrubs were merged, all calls to arc_read()
(including prefetch IOs) were given ZIO_PRIORITY_ASYNC_READ.
Unfortunately, this behaves badly with an existing issue where
prefetch IOs cannot be re-prioritized after the issue. The
result is that synchronous reads end up in the same vdev_queue
as the scrub IOs and can have (in some workloads) multiple
seconds of latency.
This patch incorporates 2 changes. The first ensures that all
scrub IOs are given ZIO_PRIORITY_SCRUB to allow the vdev_queue
code to differentiate between these I/Os and user prefetches.
Second, this patch introduces zio_change_priority() to provide
the missing capability to upgrade a zio's priority.
Reviewed by: George Wilson <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Tom Caputi <[email protected]>
Closes #6921
Closes #6926
Diffstat (limited to 'module/zfs/dsl_scan.c')
| -rw-r--r-- | module/zfs/dsl_scan.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/module/zfs/dsl_scan.c b/module/zfs/dsl_scan.c index 52c700f11..de579d1c7 100644 --- a/module/zfs/dsl_scan.c +++ b/module/zfs/dsl_scan.c @@ -1529,7 +1529,7 @@ dsl_scan_prefetch_thread(void *arg) /* issue the prefetch asynchronously */ (void) arc_read(scn->scn_zio_root, scn->scn_dp->dp_spa, &spic->spic_bp, dsl_scan_prefetch_cb, spic->spic_spc, - ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, &spic->spic_zb); + ZIO_PRIORITY_SCRUB, zio_flags, &flags, &spic->spic_zb); kmem_free(spic, sizeof (scan_prefetch_issue_ctx_t)); } @@ -1611,7 +1611,7 @@ dsl_scan_recurse(dsl_scan_t *scn, dsl_dataset_t *ds, dmu_objset_type_t ostype, arc_buf_t *buf; err = arc_read(NULL, dp->dp_spa, bp, arc_getbuf_func, &buf, - ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb); + ZIO_PRIORITY_SCRUB, zio_flags, &flags, zb); if (err) { scn->scn_phys.scn_errors++; return (err); @@ -1639,7 +1639,7 @@ dsl_scan_recurse(dsl_scan_t *scn, dsl_dataset_t *ds, dmu_objset_type_t ostype, } err = arc_read(NULL, dp->dp_spa, bp, arc_getbuf_func, &buf, - ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb); + ZIO_PRIORITY_SCRUB, zio_flags, &flags, zb); if (err) { scn->scn_phys.scn_errors++; return (err); @@ -1658,7 +1658,7 @@ dsl_scan_recurse(dsl_scan_t *scn, dsl_dataset_t *ds, dmu_objset_type_t ostype, arc_buf_t *buf; err = arc_read(NULL, dp->dp_spa, bp, arc_getbuf_func, &buf, - ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb); + ZIO_PRIORITY_SCRUB, zio_flags, &flags, zb); if (err) { scn->scn_phys.scn_errors++; return (err); |