From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx140.postini.com [74.125.245.140]) by kanga.kvack.org (Postfix) with SMTP id 73D996B0068 for ; Wed, 19 Dec 2012 17:24:06 -0500 (EST) Date: Wed, 19 Dec 2012 23:24:00 +0100 From: Zlatko Calusic MIME-Version: 1.0 References: <20121203194208.GZ24381@cmpxchg.org> <20121204214210.GB20253@cmpxchg.org> <20121205030133.GA17438@wolff.to> <20121206173742.GA27297@wolff.to> <50C32D32.6040800@iskon.hr> <50C3AF80.8040700@iskon.hr> <20121210110337.GH1009@suse.de> <20121210163904.GA22101@cmpxchg.org> <20121210180141.GK1009@suse.de> <50C62AE6.3030000@iskon.hr> <50C6477A.4090005@iskon.hr> <50C67C13.6090702@iskon.hr> In-Reply-To: <50C67C13.6090702@iskon.hr> Message-ID: <50D23E80.3010408@iskon.hr> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: kswapd craziness in 3.7 Sender: owner-linux-mm@kvack.org List-ID: To: Linus Torvalds Cc: Andrew Morton , Mel Gorman , Johannes Weiner , Rik van Riel , linux-mm , Linux Kernel Mailing List , Hugh Dickins On 11.12.2012 01:19, Zlatko Calusic wrote: >> On 10.12.2012 20:13, Linus Torvalds wrote: >>> >>> It's worth giving this as much testing as is at all possible, but at >>> the same time I really don't think I can delay 3.7 any more without >>> messing up the holiday season too much. So unless something obvious >>> pops up, I will do the release tonight. So testing will be minimal - >>> but it's not like we haven't gone back-and-forth on this several times >>> already, and we revert to *mostly* the same old state as 3.6 anyway, >>> so it should be fairly safe. >>> > > So, here's what I found. In short: close, but no cigar! > > Kswapd is certainly no more CPU pig, and memory seems to be utilized > properly (the kernel still likes to keep 400MB free, somebody else can > confirm if that's to be expected on a 4GB THP-enabled machine). So it > looks very decent, and much better than anything I run in last 10 days, > barring !THP kernel. > > What remains a mystery is that kswapd occassionaly still likes to get > stuck in a D state, only now it recovers faster than before (sometimes > in a matter of seconds, but sometimes it takes a few minutes). Now, I > admit it's a small, maybe even cosmetic issue. But, it could also be a > warning sign of a bigger problem that will reveal itself on a more > loaded machine. > Ha, I nailed it! The cigar aka the explanation together with a patch will follow shortly in a separate topic. It's a genuine bug that has been with us for a long long time. -- Zlatko -- 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