From 8e82b0714f4453bd5cf258eec3cfabae7a30617d Mon Sep 17 00:00:00 2001 From: Brian Behlendorf Date: Tue, 23 Jul 2013 15:33:23 -0700 Subject: [PATCH] Set zfs_arc_min to 4MB Decrease the mimimum ARC size from 1/32 of total system memory (or 64MB) to a much smaller 4MB. 1) Large systems with over a 1TB of memory are being deployed and reserving 1/32 of this memory (32GB) as the mimimum requirement is overkill. 2) Tiny systems like the raspberry pi may only have 256MB of memory in which case 64MB is far too large. The ARC should be reclaimable if the VFS determines it needs the memory for some other purpose. If you want to ensure the ARC is never completely reclaimed due to memory pressure you may still set a larger value with zfs_arc_min. Signed-off-by: Brian Behlendorf --- module/zfs/arc.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/module/zfs/arc.c b/module/zfs/arc.c index cbe0a6028cd3..11839af59c9f 100644 --- a/module/zfs/arc.c +++ b/module/zfs/arc.c @@ -4025,8 +4025,8 @@ arc_init(void) spl_register_shrinker(&arc_shrinker); #endif - /* set min cache to 1/32 of all memory, or 64MB, whichever is more */ - arc_c_min = MAX(arc_c / 4, 64<<20); + /* set min cache to zero */ + arc_c_min = 4<<20; /* set max to 1/2 of all memory */ arc_c_max = arc_c * 4; @@ -4036,7 +4036,7 @@ arc_init(void) */ if (zfs_arc_max > 64<<20 && zfs_arc_max < physmem * PAGESIZE) arc_c_max = zfs_arc_max; - if (zfs_arc_min > 64<<20 && zfs_arc_min <= arc_c_max) + if (zfs_arc_min > 0 && zfs_arc_min <= arc_c_max) arc_c_min = zfs_arc_min; arc_c = arc_c_max; @@ -4050,9 +4050,6 @@ arc_init(void) if (zfs_arc_meta_limit > 0 && zfs_arc_meta_limit <= arc_c_max) arc_meta_limit = zfs_arc_meta_limit; - if (arc_c_min < arc_meta_limit / 2 && zfs_arc_min == 0) - arc_c_min = arc_meta_limit / 2; - /* if kmem_flags are set, lets try to use less memory */ if (kmem_debugging()) arc_c = arc_c / 2;