The branch main has been updated by gallatin:
URL:
https://cgit.FreeBSD.org/src/commit/?id=cf907074674206b1825f79c6864c4c4a32089ecc
commit cf907074674206b1825f79c6864c4c4a32089ecc
Author: Andrew Gallatin <galla...@freebsd.org>
AuthorDate: 2025-01-15 17:11:51 +0000
Commit: Andrew Gallatin <galla...@freebsd.org>
CommitDate: 2025-01-15 17:23:00 +0000
Introduce the UMA_ZONE_NOTRIM uma zone type
The ktls buffer zone allocates 16k contiguous buffers, and often needs
to call vm_page_reclaim_contig_domain_ext() to free up contiguous
memory, which can be expensive. Web servers which have a daily
pattern of peaks and troughs end up having UMA trim the
ktls_buffer_zone when they are in their trough, and end up re-building
it on the way to their peak.
Rather than calling vm_page_reclaim_contig_domain_ext() multiple times
on a daily basis, lets mark the ktls_buffer_zone with a new UMA flag,
UMA_ZONE_NOTRIM. This disables UMA_RECLAIM_TRIM on the zone, but
allows UMA_RECLAIM_DRAIN* operations, so that if we become extremely
short of memory (vm_page_count_severe()), the uma reclaim worker can
still free up memory.
Note that UMA_ZONE_UNMANAGED already exists, but can never be drained
or trimmed, so it may hold on to memory during times of severe memory
pressure. Using UMA_ZONE_NOTRIM rather than UMA_ZONE_UNMANAGED is an
attempt to keep this zone more reactive in the face of severe memory
pressure.
Sponsored by: Netflix
Reviewed by: jhb, kib, markj (via slack)
Differential Revision: https://reviews.freebsd.org/D48451
---
sys/kern/uipc_ktls.c | 2 +-
sys/vm/uma.h | 1 +
sys/vm/uma_core.c | 11 ++++++++---
3 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/sys/kern/uipc_ktls.c b/sys/kern/uipc_ktls.c
index 881825bf1d9f..6815667594a4 100644
--- a/sys/kern/uipc_ktls.c
+++ b/sys/kern/uipc_ktls.c
@@ -495,7 +495,7 @@ ktls_init(void)
ktls_buffer_zone = uma_zcache_create("ktls_buffers",
roundup2(ktls_maxlen, PAGE_SIZE), NULL, NULL, NULL, NULL,
ktls_buffer_import, ktls_buffer_release, NULL,
- UMA_ZONE_FIRSTTOUCH);
+ UMA_ZONE_FIRSTTOUCH | UMA_ZONE_NOTRIM);
}
/*
diff --git a/sys/vm/uma.h b/sys/vm/uma.h
index 38865df7ae02..4f2b143a2fae 100644
--- a/sys/vm/uma.h
+++ b/sys/vm/uma.h
@@ -252,6 +252,7 @@ uma_zone_t uma_zcache_create(const char *name, int size,
uma_ctor ctor,
#define UMA_ZONE_SECONDARY 0x0200 /* Zone is a Secondary Zone */
#define UMA_ZONE_NOBUCKET 0x0400 /* Do not use buckets. */
#define UMA_ZONE_MAXBUCKET 0x0800 /* Use largest buckets. */
+#define UMA_ZONE_NOTRIM 0x1000 /* Don't trim this zone */
#define UMA_ZONE_CACHESPREAD 0x2000 /*
* Spread memory start locations across
* all possible cache lines. May
diff --git a/sys/vm/uma_core.c b/sys/vm/uma_core.c
index e93c561d759a..4de850afcb66 100644
--- a/sys/vm/uma_core.c
+++ b/sys/vm/uma_core.c
@@ -1222,7 +1222,7 @@ zone_timeout(uma_zone_t zone, void *unused)
trim:
/* Trim caches not used for a long time. */
- if ((zone->uz_flags & UMA_ZONE_UNMANAGED) == 0) {
+ if ((zone->uz_flags & (UMA_ZONE_UNMANAGED | UMA_ZONE_NOTRIM)) == 0) {
for (int i = 0; i < vm_ndomains; i++) {
if (bucket_cache_reclaim_domain(zone, false, false, i)
&&
(zone->uz_flags & UMA_ZFLAG_CACHE) == 0)
@@ -5306,8 +5306,13 @@ uma_reclaim_domain_cb(uma_zone_t zone, void *arg)
struct uma_reclaim_args *args;
args = arg;
- if ((zone->uz_flags & UMA_ZONE_UNMANAGED) == 0)
- uma_zone_reclaim_domain(zone, args->req, args->domain);
+ if ((zone->uz_flags & UMA_ZONE_UNMANAGED) != 0)
+ return;
+ if ((args->req == UMA_RECLAIM_TRIM) &&
+ (zone->uz_flags & UMA_ZONE_NOTRIM) !=0)
+ return;
+
+ uma_zone_reclaim_domain(zone, args->req, args->domain);
}
/* See uma.h */
