On Thu, Jan 27, 2011 at 04:27:55PM +0100, Andrea Arcangeli wrote: > totally untested... I will test.... The below patch is fixing my problem and working fine for me... as expected it can't possibly lead to any D state, it's pretty much like setting min_free_kbytes lower, and it's not going to alter anything other than the levels of free memory kept by kswapd. $ while :; do ps xa|grep [k]swapd; sleep 1; done 452 ? R 1:20 [kswapd0] 452 ? S 1:20 [kswapd0] 452 ? S 1:20 [kswapd0] 452 ? S 1:20 [kswapd0] 452 ? S 1:20 [kswapd0] 452 ? R 1:20 [kswapd0] 452 ? R 1:20 [kswapd0] 452 ? R 1:20 [kswapd0] 452 ? R 1:20 [kswapd0] 452 ? S 1:20 [kswapd0] 452 ? R 1:20 [kswapd0] $ vmstat 1 procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 2 1 1784 111040 2393336 807924 0 0 63 992 56 70 1 1 96 2 0 1 1784 108928 2402556 801864 0 0 122624 0 1619 2150 0 5 80 16 0 1 1784 110664 2401244 801140 0 0 122496 0 1602 2081 0 3 81 16 0 1 1784 109796 2410184 792984 0 0 122752 0 1685 2149 0 4 80 16 0 1 1784 110416 2411856 791208 0 0 120448 4 1599 2075 0 4 81 16 1 0 1784 113516 2415344 785336 0 0 122496 0 1636 2125 0 4 81 15 I doubt we'll get any regression because of the below (see also my prev email in this thread), and I would only expect more cache and maybe better lru. Previously the free memory levels were stuck at ~700M now they're stuck at the right level for a 4G system with THP on (I'd still like to try to reduce the requirements only 1 hugepage for each migratetype in the set_min_free_kbytes to reduce the requirements to the minium, but only if possible..). But this saves 600M over 4G so it's the highest prio to address. Comments welcome, Thanks! Andrea > ==== > Subject: vmscan: kswapd must not free more than high_wmark pages > > From: Andrea Arcangeli <aarcange@xxxxxxxxxx> > > When the min_free_kbytes is set with `hugeadm > --set-recommended-min_free_kbytes" or with THP enabled (which runs the > equivalent of "hugeadm --set-recommended-min_free_kbytes" to activate > anti-frag at full effectiveness automatically at boot) the high wmark > of some zone is as high as ~88M. 88M free on a 4G system isn't > horrible, but 88M*8 = 704M free on a 4G system is definitely > unbearable. This only tends to be visible on 4G systems with tiny > over-4g zone where kswapd insists to reach the high wmark on the > over-4g zone but doing so it shrunk up to 704M from the normal zone by > mistake. > > Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> > --- > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index f5d90de..9e3c78e 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2407,7 +2407,7 @@ loop_again: > * zone has way too many pages free already. > */ > if (!zone_watermark_ok_safe(zone, order, > - 8*high_wmark_pages(zone), end_zone, 0)) > + high_wmark_pages(zone), end_zone, 0)) > shrink_zone(priority, zone, &sc); > reclaim_state->reclaimed_slab = 0; > nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL, > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx 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>