From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f174.google.com (mail-lb0-f174.google.com [209.85.217.174]) by kanga.kvack.org (Postfix) with ESMTP id 7B616900021 for ; Wed, 29 Oct 2014 11:08:12 -0400 (EDT) Received: by mail-lb0-f174.google.com with SMTP id z11so665803lbi.19 for ; Wed, 29 Oct 2014 08:08:11 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id m7si7574180lah.97.2014.10.29.08.08.09 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 29 Oct 2014 08:08:09 -0700 (PDT) Message-ID: <545102D1.6080908@suse.cz> Date: Wed, 29 Oct 2014 16:08:01 +0100 From: Vlastimil Babka MIME-Version: 1.0 Subject: Re: isolate_freepages_block(): very high intermittent overhead References: <20141027204003.GB348@x4> <544EC0C5.7050808@suse.cz> <20141028085916.GA337@x4> In-Reply-To: <20141028085916.GA337@x4> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Markus Trippelsdorf Cc: linux-mm@kvack.org On 10/28/2014 09:59 AM, Markus Trippelsdorf wrote: > On 2014.10.27 at 23:01 +0100, Vlastimil Babka wrote: >> On 10/27/2014 09:40 PM, Markus Trippelsdorf wrote: >>> On my v3.18-rc2 kernel isolate_freepages_block() sometimes shows up very >>> high (>20%) in perf top during the configuration phase of software >>> builds. It increases build time considerably. >>> >>> Unfortunately the issue is not 100% reproducible, because it appears >>> only intermittently. And the symptoms vanish after a few minutes. >> >> Does it happen for long enough so you can capture it by perf record -g ? > > It only happens when I use the "Lockless Allocator": > http://locklessinc.com/downloads/lockless_allocator_src.tgz > > I use: LD_PRELOAD=/usr/lib/libllalloc.so.1.3 when building software, > because it gives me a ~8% speed boost over glibc's malloc. Hm I see. I'll try to test that. > Unfortunately, I don't have time to debug this further and have disabled > "Transparent Hugepage Support" for now. That's unfortunate indeed. Commit e14c720efdd73c6d69cd8d07fa894bcd11fe1973 "mm, compaction: remember position within pageblock in free pages scanner" would be the most suspicious one here I guess, so testing at least a kernel with this patch reverted would be very useful. Simple git revert seems to apply cleanly here. Thanks, Vlastimil -- 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