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uma: Use LIFO for non-SMR bucket caches

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When SMR was introduced, zone_put_bucket() was changed to always place
full buckets at the end of the queue.  However, it is generally
preferable to use recently used buckets since their items are more
likely to be resident in cache.  So, for buckets that have no constraint
on item reuse, use a last-in-first-out ordering as we did before.

Reviewed by:	rlibby
Tested by:	dhw, glebius
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D26426
This commit is contained in:
Mark Johnston 2020-10-02 19:04:09 +00:00
parent 952c8964ba
commit 5afdf5c1ca
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=366378
1 changed files with 9 additions and 1 deletions
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10
sys/vm/uma_core.c
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@ -733,7 +733,15 @@ zone_put_bucket(uma_zone_t zone, int domain, uma_bucket_t bucket, void *udata,
zone_domain_imax_set(zdom, zdom->uzd_nitems);
if (STAILQ_EMPTY(&zdom->uzd_buckets))
zdom->uzd_seq = bucket->ub_seq;
STAILQ_INSERT_TAIL(&zdom->uzd_buckets, bucket, ub_link);
/*
* Try to promote reuse of recently used items. For items
* protected by SMR, try to defer reuse to minimize polling.
*/
if (bucket->ub_seq == SMR_SEQ_INVALID)
STAILQ_INSERT_HEAD(&zdom->uzd_buckets, bucket, ub_link);
else
STAILQ_INSERT_TAIL(&zdom->uzd_buckets, bucket, ub_link);
ZDOM_UNLOCK(zdom);
return;
}