From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx136.postini.com [74.125.245.136]) by kanga.kvack.org (Postfix) with SMTP id 5EFF56B007E for ; Sun, 25 Mar 2012 15:17:02 -0400 (EDT) Received: by pbcup15 with SMTP id up15so6180309pbc.14 for ; Sun, 25 Mar 2012 12:17:01 -0700 (PDT) Date: Sun, 25 Mar 2012 12:16:26 -0700 (PDT) From: Hugh Dickins Subject: Re: [PATCH] Re: kswapd stuck using 100% CPU In-Reply-To: <20120324102621.353114da@annuminas.surriel.com> Message-ID: References: <20120324130353.48f2e4c8@kryten> <20120324102621.353114da@annuminas.surriel.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Rik van Riel Cc: Anton Blanchard , aarcange@redhat.com, mel@csn.ul.ie, akpm@linux-foundation.org, lkml , linux-mm@kvack.org, Linus Torvalds On Sat, 24 Mar 2012, Rik van Riel wrote: > > Only test compaction_suitable if the kernel is built with CONFIG_COMPACTION, > otherwise the stub compaction_suitable function will always return > COMPACT_SKIPPED and send kswapd into an infinite loop. > > Signed-off-by: Rik van Riel > Reported-by: Anton Blanchard Thank you, Anton and Rik. I never quite got around to investigating why swapping had been nearly twice as slow with linux-next on my Aspire One (with a relatively minimal config, omitting COMPACTION). That was the reason (one half of the HT cpu busy in kswapd), and this fixes it. Tested-by: Hugh Dickins > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 7658fd6..33c332b 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2946,7 +2946,8 @@ out: > continue; > > /* Would compaction fail due to lack of free memory? */ > - if (compaction_suitable(zone, order) == COMPACT_SKIPPED) > + if (COMPACTION_BUILD && > + compaction_suitable(zone, order) == COMPACT_SKIPPED) > goto loop_again; > > /* Confirm the zone is balanced for order-0 */ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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: email@kvack.org