From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964932AbcIWIIE (ORCPT ); Fri, 23 Sep 2016 04:08:04 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:35196 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758820AbcIWIHN (ORCPT ); Fri, 23 Sep 2016 04:07:13 -0400 Date: Fri, 23 Sep 2016 10:07:10 +0200 From: Michal Hocko To: Janani Ravichandran Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, riel@surriel.com, akpm@linux-foundation.org, vdavydov@virtuozzo.com, vbabka@suse.cz, mgorman@techsingularity.net, rostedt@goodmis.org Subject: Re: [RFC] scripts: Include postprocessing script for memory allocation tracing Message-ID: <20160923080709.GB4478@dhcp22.suse.cz> References: <20160911222411.GA2854@janani-Inspiron-3521> <20160912121635.GL14524@dhcp22.suse.cz> <0ACE5927-A6E5-4B49-891D-F990527A9F50@gmail.com> <20160919094224.GH10785@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 22-09-16 11:30:36, Janani Ravichandran wrote: > > > On Sep 19, 2016, at 5:42 AM, Michal Hocko wrote: > > > > On Tue 13-09-16 14:04:49, Janani Ravichandran wrote: > >> > >>> On Sep 12, 2016, at 8:16 AM, Michal Hocko wrote: > >> > >> I’m using the function graph tracer to see how long __alloc_pages_nodemask() > >> took. > > > > How can you map the function graph tracer to a specif context? Let's say > > I would like to know why a particular allocation took so long. Would > > that be possible? > > Maybe not. If the latencies are due to direct reclaim or memory compaction, you > get some information from the tracepoints (like mm_vmscan_direct_reclaim_begin, > mm_compaction_begin, etc). But otherwise, you don’t get any context information. > Function graph only gives the time spent in alloc_pages_nodemask() in that case. Then I really think that we need a starting trace point. I think that having the full context information is really helpful in order to understand latencies induced by allocations. -- Michal Hocko SUSE Labs