From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx139.postini.com [74.125.245.139]) by kanga.kvack.org (Postfix) with SMTP id 37E3D6B005D for ; Sun, 9 Dec 2012 16:59:57 -0500 (EST) Received: by mail-we0-f169.google.com with SMTP id t49so1174736wey.14 for ; Sun, 09 Dec 2012 13:59:55 -0800 (PST) Message-ID: <50C509D3.3070108@gmail.com> Date: Sun, 09 Dec 2012 22:59:47 +0100 From: Zdenek Kabelac MIME-Version: 1.0 Subject: Re: kswapd craziness in 3.7 References: <20121128145215.d23aeb1b.akpm@linux-foundation.org> <20121128235412.GW8218@suse.de> <50B77F84.1030907@leemhuis.info> <20121129170512.GI2301@cmpxchg.org> <50B8A8E7.4030108@leemhuis.info> <20121201004520.GK2301@cmpxchg.org> <50BC6314.7060106@leemhuis.info> <20121203194208.GZ24381@cmpxchg.org> <20121204214210.GB20253@cmpxchg.org> <20121205030133.GA17438@wolff.to> <20121206173742.GA27297@wolff.to> <50C32D32.6040800@iskon.hr> <50C3AF80.8040700@iskon.hr> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Linus Torvalds Cc: Zlatko Calusic , Johannes Weiner , Mel Gorman , linux-mm , Linux Kernel Mailing List Dne 9.12.2012 02:01, Linus Torvalds napsal(a): > > > On Sat, 8 Dec 2012, Zlatko Calusic wrote: >> >> Or sooner... in short: nothing's changed! >> >> On a 4GB RAM system, where applications use close to 2GB, kswapd likes to keep >> around 1GB free (unused), leaving only 1GB for page/buffer cache. If I force >> bigger page cache by reading a big file and thus use the unused 1GB of RAM, >> kswapd will soon (in a matter of minutes) evict those (or other) pages out and >> once again keep unused memory close to 1GB. > > Ok, guys, what was the reclaim or kswapd patch during the merge window > that actually caused all of these insane problems? It seems it was more > fundamentally buggered than the fifteen-million fixes for kswapd we have > already picked up. > > (Ok, I may be exaggerating the number of patches, but it's starting to > feel that way - I thought that 3.7 was going to be a calm and easy > release, but the kswapd issues seem to just keep happening. We've been > fighting the kswapd changes for a while now.) > > Trying to keep a gigabyte free (presumably because that way we have lots > of high-order alloction pages) is ridiculous. Is it one of the compaction > changes? > > Mel? Ideas? > Very true It's just as simple a making dd if=/dev/zero of=/tmp/zero bs=1M count=0 seek=1000000 and now dd if=/tmp/zero of=/dev/null bs=1M and kswapd fights with dd for CPU time.... Zdenek -- 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/ . Don't email: email@kvack.org