From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx151.postini.com [74.125.245.151]) by kanga.kvack.org (Postfix) with SMTP id B43E16B0002 for ; Tue, 2 Apr 2013 11:03:45 -0400 (EDT) Received: by mail-pa0-f49.google.com with SMTP id kp14so342518pab.36 for ; Tue, 02 Apr 2013 08:03:45 -0700 (PDT) Message-ID: <515AF348.7060209@gmail.com> Date: Tue, 02 Apr 2013 23:03:36 +0800 From: Zheng Liu MIME-Version: 1.0 Subject: Re: Excessive stall times on ext4 in 3.9-rc2 References: <20130402142717.GH32241@suse.de> In-Reply-To: <20130402142717.GH32241@suse.de> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: linux-ext4@vger.kernel.org, LKML , Linux-MM , Jiri Slaby Hi Mel, Thanks for reporting it. On 04/02/2013 10:27 PM, Mel Gorman wrote: > I'm testing a page-reclaim-related series on my laptop that is partially > aimed at fixing long stalls when doing metadata-intensive operations on > low memory such as a git checkout. I've been running 3.9-rc2 with the > series applied but found that the interactive performance was awful even > when there was plenty of free memory. > > I activated a monitor from mmtests that logs when a process is stuck for > a long time in D state and found that there are a lot of stalls in ext4. > The report first states that processes have been stalled for a total of > 6498 seconds on IO which seems like a lot. Here is a breakdown of the > recorded events. In this merge window, we add a status tree as a extent cache. Meanwhile a es_cache shrinker is registered to try to reclaim from this cache when we are under a high memory pressure. So I suspect that the root cause is this shrinker. Could you please tell me how to reproduce this problem? If I understand correctly, I can run mmtest to reproduce this problem, right? Thanks, - Zheng -- 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