Author: markj
Date: Fri Oct 18 17:36:42 2019
New Revision: 353734
URL: https://svnweb.freebsd.org/changeset/base/353734
Log:
Further constrain the use of per-CPU caches for free pages.
In low memory conditions a significant number of pages may end up stuck
in the caches, and currently these caches cannot be reaped, leading to
spurious memory allocation failures and OOM kills. So:
- Take into account the fact that we may cache up to two full buckets
of pages per CPU, not just one.
- Increase the amount of RAM required per CPU to enable the caches.
This is a temporary measure until the page cache management policy is
improved.
PR: 241048
Reported and tested by: Kevin Oberman <[email protected]>
Reviewed by: alc, kib
Discussed with: jeff
MFC after: 3 days
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D22040
Modified:
head/sys/vm/vm_page.c
Modified: head/sys/vm/vm_page.c
==============================================================================
--- head/sys/vm/vm_page.c Fri Oct 18 17:01:27 2019 (r353733)
+++ head/sys/vm/vm_page.c Fri Oct 18 17:36:42 2019 (r353734)
@@ -222,10 +222,12 @@ vm_page_init_cache_zones(void *dummy __unused)
vmd = VM_DOMAIN(domain);
/*
- * Don't allow the page caches to take up more than .25% of
- * memory.
+ * Don't allow the page caches to take up more than .1875% of
+ * memory. A UMA bucket contains at most 256 free pages, and we
+ * have two buckets per CPU per free pool.
*/
- if (vmd->vmd_page_count / 400 < 256 * mp_ncpus * VM_NFREEPOOL)
+ if (vmd->vmd_page_count / 600 < 2 * 256 * mp_ncpus *
+ VM_NFREEPOOL)
continue;
for (pool = 0; pool < VM_NFREEPOOL; pool++) {
pgcache = &vmd->vmd_pgcache[pool];
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