From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Schmitz Subject: Re: [3.13 regression] kswapd0 and ksoftirqd/0 CPU hogs Date: Tue, 07 Apr 2015 17:38:53 +1200 Message-ID: <55236D6D.5010706@gmail.com> References: <21393.43065.207399.530921@gargle.gargle.HOWL> <21426.40682.197715.245775@gargle.gargle.HOWL> <21786.40688.53001.509365@gargle.gargle.HOWL> <551B6143.4030805@gmail.com> <5522F9D5.3080107@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-pd0-f181.google.com ([209.85.192.181]:36541 "EHLO mail-pd0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750862AbbDGFi4 (ORCPT ); Tue, 7 Apr 2015 01:38:56 -0400 Received: by pdea3 with SMTP id a3so67581538pde.3 for ; Mon, 06 Apr 2015 22:38:56 -0700 (PDT) In-Reply-To: Sender: linux-m68k-owner@vger.kernel.org List-Id: linux-m68k@vger.kernel.org To: Finn Thain Cc: Mikael Pettersson , Andreas Schwab , Linux/m68k Hi Finn, > On Tue, 7 Apr 2015, Michael Schmitz wrote: > > >> The gunzip error cannot be reproduced on any of my ARAnyM VMs. Might be >> a RAM error or other hardware related problem. Same kernel but >> configured slightly different (added 030 and 040 support, plus ARAnyM >> support). >> > > The configuration differences could be cancelled by booting your new > aranym kernel on the physical hardware, and reproducing the fault that > Sure, and I'll make certain to do that once I've finished the current task (updating stuff in a current unstable chroot). > way. BTW, is this the same physical machine that has DMA issues, which we > discussed off-list in the past? > The very same. Runs fairly stable otherwise though - I would have expected filesystem corruption or other more drastic errors if the RAM was faulty. > >> The general behaviour (gunzip eats up all free RAM, then kswapd spins >> doing nothing very apparent, with no dirty pages to be flushed and >> cached pages never released) remains the same. Though I've seen the >> gunzip complete without kicking off kswapd on occasion (had set >> dirty_background_ratio and dirty_ratio half the default for that). >> >> And yes, dropping cached pages as Andreas suggested, does free up >> significant (i.e. most of all) RAM and shuts up kswapd. >> > > This bug has been reported to Red Hat in the past (on x86_64). They closed > the bugzilla entry in 2011, but the bug was still being reported by Fedora > users in 2014. https://bugzilla.redhat.com/show_bug.cgi?id=712019 > Thanks for pointing that out! The patches attached to this report made it into Linus' git tree at that time so I presume we are seeing something closely related. The discussion on LRML makes my head spin - not a chance to debug this in a meaningful way, I suppose. Michael