Author: mjg
Date: Tue Sep 10 20:11:00 2019
New Revision: 352178
URL: https://svnweb.freebsd.org/changeset/base/352178
Log:
cache: change the formula for calculating lock array sizes
It used to be mp_ncpus * 64, but this gives unnecessarily big values for small
machines and at the same time constraints bigger ones. In particular this
helps
on a 104-way box for which the count is now doubled.
While here make cache_purgevfs less likely. Currently it is not efficient in
face of contention due to lock ordering issues. These are fixable but not
worth
it at the moment.
Sponsored by: The FreeBSD Foundation
Modified:
head/sys/kern/vfs_cache.c
Modified: head/sys/kern/vfs_cache.c
==============================================================================
--- head/sys/kern/vfs_cache.c Tue Sep 10 20:08:24 2019 (r352177)
+++ head/sys/kern/vfs_cache.c Tue Sep 10 20:11:00 2019 (r352178)
@@ -1879,19 +1879,21 @@ nchinit(void *dummy __unused)
UMA_ZONE_ZINIT);
nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash);
- ncbuckethash = cache_roundup_2(mp_ncpus * 64) - 1;
+ ncbuckethash = cache_roundup_2(mp_ncpus * mp_ncpus) - 1;
+ if (ncbuckethash < 7) /* arbitrarily chosen to avoid having one lock */
+ ncbuckethash = 7;
if (ncbuckethash > nchash)
ncbuckethash = nchash;
bucketlocks = malloc(sizeof(*bucketlocks) * numbucketlocks, M_VFSCACHE,
M_WAITOK | M_ZERO);
for (i = 0; i < numbucketlocks; i++)
rw_init_flags(&bucketlocks[i], "ncbuc", RW_DUPOK | RW_RECURSE);
- ncvnodehash = cache_roundup_2(mp_ncpus * 64) - 1;
+ ncvnodehash = ncbuckethash;
vnodelocks = malloc(sizeof(*vnodelocks) * numvnodelocks, M_VFSCACHE,
M_WAITOK | M_ZERO);
for (i = 0; i < numvnodelocks; i++)
mtx_init(&vnodelocks[i], "ncvn", NULL, MTX_DUPOK | MTX_RECURSE);
- ncpurgeminvnodes = numbucketlocks;
+ ncpurgeminvnodes = numbucketlocks * 2;
ncneghash = 3;
neglists = malloc(sizeof(*neglists) * numneglists, M_VFSCACHE,
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