From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mikael Pettersson Subject: Re: [3.13 regression] kswapd0 and ksoftirqd/0 CPU hogs Date: Sat, 7 Jun 2014 15:22:55 +0200 Message-ID: <21395.4655.114256.170707@gargle.gargle.HOWL> References: <21393.43065.207399.530921@gargle.gargle.HOWL> <21393.48632.521704.579850@gargle.gargle.HOWL> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from mail-la0-f49.google.com ([209.85.215.49]:53881 "EHLO mail-la0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752590AbaFGNXA (ORCPT ); Sat, 7 Jun 2014 09:23:00 -0400 Received: by mail-la0-f49.google.com with SMTP id pv20so2159915lab.36 for ; Sat, 07 Jun 2014 06:22:58 -0700 (PDT) In-Reply-To: <21393.48632.521704.579850@gargle.gargle.HOWL> Sender: linux-m68k-owner@vger.kernel.org List-Id: linux-m68k@vger.kernel.org To: Mikael Pettersson Cc: Geert Uytterhoeven , Linux/m68k Mikael Pettersson writes: > Geert Uytterhoeven writes: > > Hi Mikael, > > > > On Fri, Jun 6, 2014 at 1:38 PM, Mikael Pettersson wrote: > > > Since updating my ARAnym VMs from 3.12.16 to 3.13.11 I see kswapd0 > > > and ksoftirqd/0 consume inordinate amounts of CPU. kswapd0 often > > > rises to about 30-50% CPU even though RAM shouldn't be anywhere near > > > depleted (768GB, a gcc bootstrap running in a screen session). > > > kswapd0 tends to stay this way until I drop caches, but doing that > > > doesn't always fix it. I also sometimes see ksoftirqd/0 consume > > > 5-30% CPU. > > > > > > Reverting to 3.12.16 completely eliminates these problems. > > > > Any chance to bisect it? > > > > > I haven't tested 3.14 or 3.15-rc yet. > > > > Would be good to know, though, as it may have been fixed. > > However, as v3.13.11 is the most recent stable version of v3.13, this may be > > an elsewhere unknown and thus unfixed issue. > > I've just started a gcc-4.8 bootstrap on 3.14.5, and then I'll try 3.15 > if it isn't fixed in 3.14. 3.14.5 is also affected by the bug. Dropping caches fixed kswapd0, but instead ksoftirqd/0 jumped to 20-40%, and it refuses to calm down.