From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757648AbbA0KeJ (ORCPT ); Tue, 27 Jan 2015 05:34:09 -0500 Received: from smtp.codeaurora.org ([198.145.11.231]:46909 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753338AbbA0KeG (ORCPT ); Tue, 27 Jan 2015 05:34:06 -0500 Message-ID: <54C76995.70501@codeaurora.org> Date: Tue, 27 Jan 2015 16:03:57 +0530 From: Vinayak Menon User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130329 Thunderbird/17.0.5 MIME-Version: 1.0 To: Michal Hocko CC: Christoph Lameter , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, hannes@cmpxchg.org, vdavydov@parallels.com, mgorman@suse.de, minchan@kernel.org Subject: Re: [PATCH v2] mm: vmscan: fix the page state calculation in too_many_isolated References: <1421235419-30736-1-git-send-email-vinmenon@codeaurora.org> <20150114165036.GI4706@dhcp22.suse.cz> <54B7F7C4.2070105@codeaurora.org> <20150116154922.GB4650@dhcp22.suse.cz> <54BA7D3A.40100@codeaurora.org> <20150126172832.GC22681@dhcp22.suse.cz> In-Reply-To: <20150126172832.GC22681@dhcp22.suse.cz> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/26/2015 10:58 PM, Michal Hocko wrote: > On Sat 17-01-15 13:48:34, Christoph Lameter wrote: >> On Sat, 17 Jan 2015, Vinayak Menon wrote: >> >>> which had not updated the vmstat_diff. This CPU was in idle for around 30 >>> secs. When I looked at the tvec base for this CPU, the timer associated with >>> vmstat_update had its expiry time less than current jiffies. This timer had >>> its deferrable flag set, and was tied to the next non-deferrable timer in the >> >> We can remove the deferrrable flag now since the vmstat threads are only >> activated as necessary with the recent changes. Looks like this could fix >> your issue? > > OK, I have checked the history and the deferrable behavior has been > introduced by 39bf6270f524 (VM statistics: Make timer deferrable) which > hasn't offered any numbers which would justify the change. So I think it > would be a good idea to revert this one as it can clearly cause issues. > > Could you retest with this change? It still wouldn't help with the > highly overloaded workqueues but that sounds like a bigger change and > this one sounds like quite safe to me so it is a good start. Sure, I can retest. Even without highly overloaded workqueues, there can be a delay of HZ in updating the counters. This means reclaim path can be blocked for a second or more, when there aren't really any isolated pages. So we need the fix in too_many_isolated also right ? -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation