From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752806AbbANQul (ORCPT ); Wed, 14 Jan 2015 11:50:41 -0500 Received: from mail-wg0-f42.google.com ([74.125.82.42]:54152 "EHLO mail-wg0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751706AbbANQuk (ORCPT ); Wed, 14 Jan 2015 11:50:40 -0500 Date: Wed, 14 Jan 2015 17:50:36 +0100 From: Michal Hocko To: Vinayak Menon Cc: 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 Message-ID: <20150114165036.GI4706@dhcp22.suse.cz> References: <1421235419-30736-1-git-send-email-vinmenon@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1421235419-30736-1-git-send-email-vinmenon@codeaurora.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 14-01-15 17:06:59, Vinayak Menon wrote: [...] > In one such instance, zone_page_state(zone, NR_ISOLATED_FILE) > had returned 14, zone_page_state(zone, NR_INACTIVE_FILE) > returned 92, and GFP_IOFS was set, and this resulted > in too_many_isolated returning true. But one of the CPU's > pageset vm_stat_diff had NR_ISOLATED_FILE as "-14". So the > actual isolated count was zero. As there weren't any more > updates to NR_ISOLATED_FILE and vmstat_update deffered work > had not been scheduled yet, 7 tasks were spinning in the > congestion wait loop for around 4 seconds, in the direct > reclaim path. Not syncing for such a long time doesn't sound right. I am not familiar with the vmstat syncing but sysctl_stat_interval is HZ so it should happen much more often that every 4 seconds. -- Michal Hocko SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f49.google.com (mail-wg0-f49.google.com [74.125.82.49]) by kanga.kvack.org (Postfix) with ESMTP id 5C8846B006C for ; Wed, 14 Jan 2015 11:50:40 -0500 (EST) Received: by mail-wg0-f49.google.com with SMTP id n12so10061316wgh.8 for ; Wed, 14 Jan 2015 08:50:39 -0800 (PST) Received: from mail-wi0-x234.google.com (mail-wi0-x234.google.com. [2a00:1450:400c:c05::234]) by mx.google.com with ESMTPS id t3si4487901wiw.92.2015.01.14.08.50.39 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 14 Jan 2015 08:50:39 -0800 (PST) Received: by mail-wi0-f180.google.com with SMTP id n3so12243367wiv.1 for ; Wed, 14 Jan 2015 08:50:39 -0800 (PST) Date: Wed, 14 Jan 2015 17:50:36 +0100 From: Michal Hocko Subject: Re: [PATCH v2] mm: vmscan: fix the page state calculation in too_many_isolated Message-ID: <20150114165036.GI4706@dhcp22.suse.cz> References: <1421235419-30736-1-git-send-email-vinmenon@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1421235419-30736-1-git-send-email-vinmenon@codeaurora.org> Sender: owner-linux-mm@kvack.org List-ID: To: Vinayak Menon Cc: 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 On Wed 14-01-15 17:06:59, Vinayak Menon wrote: [...] > In one such instance, zone_page_state(zone, NR_ISOLATED_FILE) > had returned 14, zone_page_state(zone, NR_INACTIVE_FILE) > returned 92, and GFP_IOFS was set, and this resulted > in too_many_isolated returning true. But one of the CPU's > pageset vm_stat_diff had NR_ISOLATED_FILE as "-14". So the > actual isolated count was zero. As there weren't any more > updates to NR_ISOLATED_FILE and vmstat_update deffered work > had not been scheduled yet, 7 tasks were spinning in the > congestion wait loop for around 4 seconds, in the direct > reclaim path. Not syncing for such a long time doesn't sound right. I am not familiar with the vmstat syncing but sysctl_stat_interval is HZ so it should happen much more often that every 4 seconds. -- Michal Hocko SUSE Labs -- 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