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: Fri, 6 Jun 2014 15:11:20 +0200 Message-ID: <21393.48632.521704.579850@gargle.gargle.HOWL> References: <21393.43065.207399.530921@gargle.gargle.HOWL> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from mail-la0-f54.google.com ([209.85.215.54]:50129 "EHLO mail-la0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751791AbaFFNLZ (ORCPT ); Fri, 6 Jun 2014 09:11:25 -0400 Received: by mail-la0-f54.google.com with SMTP id pv20so1533742lab.13 for ; Fri, 06 Jun 2014 06:11:23 -0700 (PDT) In-Reply-To: Sender: linux-m68k-owner@vger.kernel.org List-Id: linux-m68k@vger.kernel.org To: Geert Uytterhoeven Cc: Mikael Pettersson , Linux/m68k 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. If 3.15 too is broken, I'll do the bisect, but it will be a slow process since it takes anywhere from a few hours to a couple of days for the bug to appear. BTW, the presence of some unknown bug causing kswapd0 to hog the CPU has been mentioned on the Debian m68k list earlier this year. /Mikael