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MFC r275738: MFV r275546:

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Reduce scrub activities when system there is enough dirty data, namely when
dirty data is more than zfs_vdev_async_write_active_min_dirty_percent (once
we start to increase the number of concurrent async writes).

While there also correct rounding error which would make scrub end up
pausing for (zfs_txg_timeout + 1) seconds instead of the desired
zfs_txg_timeout seconds.

Illumos issue:
    5351 scrub goes for an extra second each txg
    5352 scrub should pause when there is some dirty data
This commit is contained in:
delphij 2015-01-23 17:41:34 +00:00
parent 85cd2fc0bf
commit 9a50f3f3a8
1 changed files with 22 additions and 7 deletions
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29
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scan.c
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@ -423,12 +423,11 @@ dsl_scan_sync_state(dsl_scan_t *scn, dmu_tx_t *tx)
&scn->scn_phys, tx));
}
extern int zfs_vdev_async_write_active_min_dirty_percent;
static boolean_t
dsl_scan_check_pause(dsl_scan_t *scn, const zbookmark_phys_t *zb)
{
uint64_t elapsed_nanosecs;
unsigned int mintime;
/* we never skip user/group accounting objects */
if (zb && (int64_t)zb->zb_object < 0)
return (B_FALSE);
@ -443,12 +442,28 @@ dsl_scan_check_pause(dsl_scan_t *scn, const zbookmark_phys_t *zb)
if (zb && zb->zb_level != 0)
return (B_FALSE);
mintime = (scn->scn_phys.scn_func == POOL_SCAN_RESILVER) ?
/*
* We pause if:
* - we have scanned for the maximum time: an entire txg
* timeout (default 5 sec)
* or
* - we have scanned for at least the minimum time (default 1 sec
* for scrub, 3 sec for resilver), and either we have sufficient
* dirty data that we are starting to write more quickly
* (default 30%), or someone is explicitly waiting for this txg
* to complete.
* or
* - the spa is shutting down because this pool is being exported
* or the machine is rebooting.
*/
int mintime = (scn->scn_phys.scn_func == POOL_SCAN_RESILVER) ?
zfs_resilver_min_time_ms : zfs_scan_min_time_ms;
elapsed_nanosecs = gethrtime() - scn->scn_sync_start_time;
if (elapsed_nanosecs / NANOSEC > zfs_txg_timeout ||
uint64_t elapsed_nanosecs = gethrtime() - scn->scn_sync_start_time;
int dirty_pct = scn->scn_dp->dp_dirty_total * 100 / zfs_dirty_data_max;
if (elapsed_nanosecs / NANOSEC >= zfs_txg_timeout ||
(NSEC2MSEC(elapsed_nanosecs) > mintime &&
txg_sync_waiting(scn->scn_dp)) ||
(txg_sync_waiting(scn->scn_dp) ||
dirty_pct >= zfs_vdev_async_write_active_min_dirty_percent)) ||
spa_shutting_down(scn->scn_dp->dp_spa)) {
if (zb) {
dprintf("pausing at bookmark %llx/%llx/%llx/%llx\n",