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Allow skipping dmu_buf_will_dirty() call in dsl_dir_transfer_space().

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dsl_dir_transfer_space() is mostly called after dsl_dir_diduse_space(),
which already calls dmu_buf_will_dirty() for the same dbuf and tx, so
its duplicate call in those cases will change nothing, only spend time.

Skipping this call by four times reduces time spent in dbuf_write_done()
and descendants, updating dataset statistics with several congested lock
acquisitions.  When rewriting 8K zvol blocks at 1GB/s rate, this reduces
CPU time spent inside dbuf_write_done(), according to profiling, from 45%
of 683K samples to 18% of 422K.

MFC after:	2 weeks
This commit is contained in:
Alexander Motin 2015-01-20 13:09:12 +00:00
parent b829c841ad
commit d6245e3d44
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=277419
2 changed files with 7 additions and 6 deletions
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6
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dataset.c
View File

@ -136,7 +136,7 @@ dsl_dataset_block_born(dsl_dataset_t *ds, const blkptr_t *bp, dmu_tx_t *tx)
dsl_dir_diduse_space(ds->ds_dir, DD_USED_HEAD, delta,
compressed, uncompressed, tx);
dsl_dir_transfer_space(ds->ds_dir, used - delta,
DD_USED_REFRSRV, DD_USED_HEAD, tx);
DD_USED_REFRSRV, DD_USED_HEAD, NULL);
}
int
@ -179,7 +179,7 @@ dsl_dataset_block_kill(dsl_dataset_t *ds, const blkptr_t *bp, dmu_tx_t *tx,
dsl_dir_diduse_space(ds->ds_dir, DD_USED_HEAD,
delta, -compressed, -uncompressed, tx);
dsl_dir_transfer_space(ds->ds_dir, -used - delta,
DD_USED_REFRSRV, DD_USED_HEAD, tx);
DD_USED_REFRSRV, DD_USED_HEAD, NULL);
} else {
dprintf_bp(bp, "putting on dead list: %s", "");
if (async) {
@ -2837,7 +2837,7 @@ dsl_dataset_clone_swap_sync_impl(dsl_dataset_t *clone,
origin_head->ds_dir->dd_origin_txg, UINT64_MAX,
&odl_used, &odl_comp, &odl_uncomp);
dsl_dir_transfer_space(origin_head->ds_dir, cdl_used - odl_used,
DD_USED_HEAD, DD_USED_SNAP, tx);
DD_USED_HEAD, DD_USED_SNAP, NULL);
}
/* swap ds_*_bytes */

7
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_dir.c
View File

@ -1389,7 +1389,7 @@ dsl_dir_diduse_space(dsl_dir_t *dd, dd_used_t type,
accounted_delta, compressed, uncompressed, tx);
dsl_dir_transfer_space(dd->dd_parent,
used - accounted_delta,
DD_USED_CHILD_RSRV, DD_USED_CHILD, tx);
DD_USED_CHILD_RSRV, DD_USED_CHILD, NULL);
}
}
@ -1397,7 +1397,7 @@ void
dsl_dir_transfer_space(dsl_dir_t *dd, int64_t delta,
dd_used_t oldtype, dd_used_t newtype, dmu_tx_t *tx)
{
ASSERT(dmu_tx_is_syncing(tx));
ASSERT(tx == NULL || dmu_tx_is_syncing(tx));
ASSERT(oldtype < DD_USED_NUM);
ASSERT(newtype < DD_USED_NUM);
@ -1405,7 +1405,8 @@ dsl_dir_transfer_space(dsl_dir_t *dd, int64_t delta,
!(dsl_dir_phys(dd)->dd_flags & DD_FLAG_USED_BREAKDOWN))
return;
dmu_buf_will_dirty(dd->dd_dbuf, tx);
if (tx != NULL)
dmu_buf_will_dirty(dd->dd_dbuf, tx);
mutex_enter(&dd->dd_lock);
ASSERT(delta > 0 ?
dsl_dir_phys(dd)->dd_used_breakdown[oldtype] >= delta :