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9751 Allocation throttling misplacing ditto blocks

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Relax allocation throttling for ditto blocks.  Due to random imbalances
in allocation it tends to push block copies to one vdev, that looks
slightly better at the moment.  Slightly less strict policy allows both
improve data security and surprisingly write performance, since we don't
need to touch extra metaslabs on each vdev to respect the min distance.

Sponsored by:	iXsystems, Inc.
This commit is contained in:
Alexander Motin 2018-08-17 15:17:09 +00:00
parent 2848a0e2da
commit cd2315086a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=337972
1 changed files with 10 additions and 3 deletions
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13
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/metaslab.c
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@ -1081,7 +1081,7 @@ metaslab_group_fragmentation(metaslab_group_t *mg)
*/
static boolean_t
metaslab_group_allocatable(metaslab_group_t *mg, metaslab_group_t *rotor,
uint64_t psize, int allocator)
uint64_t psize, int allocator, int d)
{
spa_t *spa = mg->mg_vd->vdev_spa;
metaslab_class_t *mc = mg->mg_class;
@ -1122,6 +1122,13 @@ metaslab_group_allocatable(metaslab_group_t *mg, metaslab_group_t *rotor,
if (mg->mg_no_free_space)
return (B_FALSE);
/*
* Relax allocation throttling for ditto blocks. Due to
* random imbalances in allocation it tends to push copies
* to one vdev, that looks a bit better at the moment.
*/
qmax = qmax * (4 + d) / 4;
qdepth = refcount_count(&mg->mg_alloc_queue_depth[allocator]);
/*
@ -1142,7 +1149,7 @@ metaslab_group_allocatable(metaslab_group_t *mg, metaslab_group_t *rotor,
*/
for (mgp = mg->mg_next; mgp != rotor; mgp = mgp->mg_next) {
qmax = mgp->mg_cur_max_alloc_queue_depth[allocator];
qmax = qmax * (4 + d) / 4;
qdepth = refcount_count(
&mgp->mg_alloc_queue_depth[allocator]);
@ -3424,7 +3431,7 @@ metaslab_alloc_dva(spa_t *spa, metaslab_class_t *mc, uint64_t psize,
*/
if (allocatable && !GANG_ALLOCATION(flags) && !try_hard) {
allocatable = metaslab_group_allocatable(mg, rotor,
psize, allocator);
psize, allocator, d);
}
if (!allocatable) {