From: Hugh Dickins <hughd@google.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Sasha Levin <levinsasha928@gmail.com>,
Minchan Kim <minchan@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: [PATCH] mm: raise MemFree by reverting percpu_pagelist_fraction to 0
Date: Fri, 11 May 2012 01:00:07 -0700 (PDT) [thread overview]
Message-ID: <alpine.LSU.2.00.1205110054520.2801@eggly.anvils> (raw)
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 <hughd@google.com>
---
mm/page_alloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- 3.4-rc6+/mm/page_alloc.c 2012-05-10 22:53:35.362478419 -0700
+++ linux/mm/page_alloc.c 2012-05-11 00:07:31.613657283 -0700
@@ -105,7 +105,7 @@ unsigned long totalreserve_pages __read_
*/
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;
#ifdef CONFIG_PM_SLEEP
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next reply other threads:[~2012-05-11 8:00 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-11 8:00 Hugh Dickins [this message]
2012-05-11 8:30 ` Sasha Levin
2012-05-11 8:38 ` Minchan Kim
2012-05-11 9:01 ` Minchan Kim
2012-05-11 16:27 ` Linus Torvalds
2012-05-11 16:35 ` Sasha Levin
2012-05-11 16:54 ` Linus Torvalds
2012-05-14 8:51 ` Cong Wang
2012-05-11 14:10 ` Hugh Dickins
2012-05-14 1:51 ` Minchan Kim
2012-05-11 16:26 ` Linus Torvalds
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