Author: avg
Date: Tue Oct 7 16:08:21 2014
New Revision: 272708
URL: https://svnweb.freebsd.org/changeset/base/272708
Log:
l2arc_write_buffers: reduce headroom value
FreeBSD has ARC_BUFC_NUMMETADATALISTS metadata lists and ARC_BUFC_NUMDATALISTS
data lists (currently both are 16) while illumos has just a single list
of each kind.
headroom determines how much data is scanned on a single list
during each run of the l2arc feed thread.
Because FreeBSD has more lists we proportionally decrease the limit.
Reviewed by: Brendan Gregg (earlier version)
MFC after: 2 weeks
Sponsored by: HybridCluster
Modified:
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c Tue Oct 7
16:06:10 2014 (r272707)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c Tue Oct 7
16:08:21 2014 (r272708)
@@ -5047,7 +5047,7 @@ l2arc_write_buffers(spa_t *spa, l2arc_de
if (ab == NULL)
ARCSTAT_BUMP(arcstat_l2_write_buffer_list_null_iter);
- headroom = target_sz * l2arc_headroom;
+ headroom = target_sz * l2arc_headroom * 2 / ARC_BUFC_NUMLISTS;
if (do_headroom_boost)
headroom = (headroom * l2arc_headroom_boost) / 100;
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