diff options
authorHugh Dickins <>2012-05-11 01:00:07 -0700
committerLinus Torvalds <>2012-05-11 09:23:39 -0700
commit1b76b02f15c70d5f392ee2e231fbd20a26063a77 (patch)
parentd60b9c16d7bae49b75255520abd7dfd2e94627bc (diff)
mm: raise MemFree by reverting percpu_pagelist_fraction to 0
Why is there less MemFree than there used to be? It perturbed a test, so I've just been bisecting linux-next, and now find the offender went upstream yesterday. Commit 93278814d359 "mm: fix division by 0 in percpu_pagelist_fraction()" mistakenly initialized percpu_pagelist_fraction to the sysctl's minimum 8, which leaves 1/8th of memory on percpu lists (on each cpu??); but most of us expect it to be left unset at 0 (and it's not then used as a divisor). MemTotal: 8061476kB 8061476kB 8061476kB 8061476kB 8061476kB 8061476kB Repetitive test with percpu_pagelist_fraction 8: MemFree: 6948420kB 6237172kB 6949696kB 6840692kB 6949048kB 6862984kB Same test with percpu_pagelist_fraction back to 0: MemFree: 7945000kB 7944908kB 7948568kB 7949060kB 7948796kB 7948812kB Signed-off-by: Hugh Dickins <> [ We really should fix the crazy sysctl interface too, but that's a separate thing - Linus ] Signed-off-by: Linus Torvalds <>
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b21b3db15a7f..918330f71dba 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -105,7 +105,7 @@ unsigned long totalreserve_pages __read_mostly;
unsigned long dirty_balance_reserve __read_mostly;
-int percpu_pagelist_fraction = 8;
+int percpu_pagelist_fraction;
gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;