Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757416Ab1ELW6U (ORCPT ); Thu, 12 May 2011 18:58:20 -0400 Received: from mail-qy0-f174.google.com ([209.85.216.174]:41267 "EHLO mail-qy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756240Ab1ELW6T convert rfc822-to-8bit (ORCPT ); Thu, 12 May 2011 18:58:19 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=qqijDYRAbeoJfiteRNoZPQSEA5eedQ2k1Jrfnm8nD6qHgUONB8XQZGRjCUmO1Z0v/H pYG3zJKfXfpsv90Oyy/z/M86w3y7kO+ys55LP7FQi9GmpEk8xQf+9SPTwGwRuDmt+MsH WroAa9X556yrFMP9MiR7RpYCVv1pB/ysu4vS8= MIME-Version: 1.0 In-Reply-To: <20110512221506.GM16531@cmpxchg.org> References: <1305127773-10570-4-git-send-email-mgorman@suse.de> <1305213359.2575.46.camel@mulgrave.site> <1305214993.2575.50.camel@mulgrave.site> <1305215742.27848.40.camel@jaguar> <1305225467.2575.66.camel@mulgrave.site> <1305229447.2575.71.camel@mulgrave.site> <1305230652.2575.72.camel@mulgrave.site> <1305237882.2575.100.camel@mulgrave.site> <20110512221506.GM16531@cmpxchg.org> Date: Fri, 13 May 2011 07:58:17 +0900 Message-ID: Subject: Re: [PATCH 3/3] mm: slub: Default slub_max_order to 0 From: Minchan Kim To: Johannes Weiner Cc: James Bottomley , Pekka Enberg , Christoph Lameter , Mel Gorman , Andrew Morton , Colin King , Raghavendra D Prabhu , Jan Kara , Chris Mason , Rik van Riel , linux-fsdevel , linux-mm , linux-kernel , linux-ext4 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2469 Lines: 61 On Fri, May 13, 2011 at 7:15 AM, Johannes Weiner wrote: > On Thu, May 12, 2011 at 05:04:41PM -0500, James Bottomley wrote: >> On Thu, 2011-05-12 at 15:04 -0500, James Bottomley wrote: >> > Confirmed, I'm afraid ... I can trigger the problem with all three >> > patches under PREEMPT.  It's not a hang this time, it's just kswapd >> > taking 100% system time on 1 CPU and it won't calm down after I unload >> > the system. >> >> Just on a "if you don't know what's wrong poke about and see" basis, I >> sliced out all the complex logic in sleeping_prematurely() and, as far >> as I can tell, it cures the problem behaviour.  I've loaded up the >> system, and taken the tar load generator through three runs without >> producing a spinning kswapd (this is PREEMPT).  I'll try with a >> non-PREEMPT kernel shortly. >> >> What this seems to say is that there's a problem with the complex logic >> in sleeping_prematurely().  I'm pretty sure hacking up >> sleeping_prematurely() just to dump all the calculations is the wrong >> thing to do, but perhaps someone can see what the right thing is ... > > I think I see the problem: the boolean logic of sleeping_prematurely() > is odd.  If it returns true, kswapd will keep running.  So if > pgdat_balanced() returns true, kswapd should go to sleep. > > This? Yes. Good catch. > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 2b701e0..092d773 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2261,7 +2261,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining, >         * must be balanced >         */ >        if (order) > -               return pgdat_balanced(pgdat, balanced, classzone_idx); > +               return !pgdat_balanced(pgdat, balanced, classzone_idx); >        else >                return !all_zones_ok; >  } > > -- > 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/ . > Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ > Don't email: email@kvack.org > -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/