From 518b4876022eee58b14903da09b99c01b8caa754 Mon Sep 17 00:00:00 2001 From: Richard Yao Date: Thu, 12 Apr 2012 17:22:08 -0400 Subject: [PATCH] Update ARC memory limits to account for SLUB internal fragmentation 23bdb07d4e4c435205d25d3efdb5fef2d089ce5e updated the ARC memory limits to be 1/2 of memory or all but 4GB. Unfortunately, these values assume zero internal fragmentation in the SLUB allocator, when in reality, the internal fragmentation could be as high as 50%, effectively doubling memory usage. This poses clear safety issues, because it permits the size of ARC to exceed system memory. This patch changes this so that the default value of arc_c_max is always 1/2 of system memory. This effectively limits the ARC to the memory that the system has physically installed. Signed-off-by: Brian Behlendorf Closes #660 --- module/zfs/arc.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/module/zfs/arc.c b/module/zfs/arc.c index d6eaa6cf0..7aa23ca15 100644 --- a/module/zfs/arc.c +++ b/module/zfs/arc.c @@ -3723,11 +3723,7 @@ arc_init(void) /* set min cache to 1/32 of all memory, or 64MB, whichever is more */ arc_c_min = MAX(arc_c / 4, 64<<20); - /* set max to 1/2 of all memory, or all but 4GB, whichever is more */ - if (arc_c * 8 >= ((uint64_t)4<<30)) - arc_c_max = (arc_c * 8) - ((uint64_t)4<<30); - else - arc_c_max = arc_c_min; + /* set max to 1/2 of all memory */ arc_c_max = MAX(arc_c * 4, arc_c_max); /*