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@xxxxxxxxxx> --- 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>