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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:
markj 2020-10-02 19:04:09 +00:00
parent fcc5c7bb1a
commit 5ce4e6412e
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;
}