>> I think this only correct when memcg. Even if swappiness==0, global reclaim swap >> out anon pages before oom. > > Right you are (we really do swap when the file pages are really > low)! Sorry about the confusion. I kind of became if(global_reclaim) > block blind... > > Then this really needs a memcg specific documentation fix. What about > the following? > --- > From 59a60705abd2faf9e266a4270bbf302001845588 Mon Sep 17 00:00:00 2001 > From: Michal Hocko <mhocko@xxxxxxx> > Date: Mon, 15 Oct 2012 11:43:56 +0200 > Subject: [PATCH] doc: describe memcg swappiness more precisely > > since fe35004f (mm: avoid swapping out with swappiness==0) memcg reclaim > stopped swapping out anon pages completely when 0 value is used. > Although this is somehow expected it hasn't been done for a really long > time this way and so it is probably better to be explicit about the > effect. Moreover global reclaim swapps out even when swappiness is 0 > to prevent from OOM killer. > > Signed-off-by: Michal Hocko <mhocko@xxxxxxx> > --- > Documentation/cgroups/memory.txt | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt > index c07f7b4..71c4da4 100644 > --- a/Documentation/cgroups/memory.txt > +++ b/Documentation/cgroups/memory.txt > @@ -466,6 +466,10 @@ Note: > 5.3 swappiness > > Similar to /proc/sys/vm/swappiness, but affecting a hierarchy of groups only. > +Please note that unlike the global swappiness, memcg knob set to 0 > +really prevents from any swapping even if there is a swap storage > +available. This might lead to memcg OOM killer if there are no file > +pages to reclaim. Pretty good to me. Thank you! Acked-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>