From 121b3cae742a0670d902a51bc61d49dc4a3e4445 Mon Sep 17 00:00:00 2001 From: Tim Chase Date: Thu, 4 Jun 2015 08:06:27 -0500 Subject: [PATCH] Increase arc_c_min to allow safe operation of arc_adapt() ZoL had lowered the minimum ARC size to 4MiB to better accommodate tiny systems such as the raspberry pi, however, as of addition of large block support, the arc_adapt() function depends on arc_c being >= 32MiB (2 * SPA_MAXBLOCKSIZE). This patch raises the minimum ARC size to 32MiB and adds a VERIFY test to arc_adapt() for future-proofing. Signed-off-by: Tim Chase Signed-off-by: Brian Behlendorf --- module/zfs/arc.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/module/zfs/arc.c b/module/zfs/arc.c index 561c23124..805e7b59f 100644 --- a/module/zfs/arc.c +++ b/module/zfs/arc.c @@ -3088,8 +3088,8 @@ arc_adapt_thread(void) zfs_arc_max != arc_c_max) arc_c_max = zfs_arc_max; - if (zfs_arc_min > 0 && - zfs_arc_min < arc_c_max && + if (zfs_arc_min >= 2ULL << SPA_MAXBLOCKSHIFT && + zfs_arc_min <= arc_c_max && zfs_arc_min != arc_c_min) arc_c_min = zfs_arc_min; @@ -3355,7 +3355,8 @@ arc_adapt(int bytes, arc_state_t *state) * If we're within (2 * maxblocksize) bytes of the target * cache size, increment the target cache size */ - if (arc_size > arc_c - (2ULL << SPA_MAXBLOCKSHIFT)) { + VERIFY3U(arc_c, >=, 2ULL << SPA_MAXBLOCKSHIFT); + if (arc_size >= arc_c - (2ULL << SPA_MAXBLOCKSHIFT)) { atomic_add_64(&arc_c, (int64_t)bytes); if (arc_c > arc_c_max) arc_c = arc_c_max; @@ -4826,8 +4827,8 @@ arc_init(void) spl_register_shrinker(&arc_shrinker); #endif - /* set min cache to zero */ - arc_c_min = 4<<20; + /* set min cache to allow safe operation of arc_adapt() */ + arc_c_min = 2ULL << SPA_MAXBLOCKSHIFT; /* set max to 1/2 of all memory */ arc_c_max = arc_c * 4; @@ -4837,7 +4838,8 @@ arc_init(void) */ if (zfs_arc_max > 64<<20 && zfs_arc_max < physmem * PAGESIZE) arc_c_max = zfs_arc_max; - if (zfs_arc_min > 0 && zfs_arc_min <= arc_c_max) + if (zfs_arc_min >= 2ULL << SPA_MAXBLOCKSHIFT && + zfs_arc_min <= arc_c_max) arc_c_min = zfs_arc_min; arc_c = arc_c_max;