From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758162Ab2CSHhi (ORCPT ); Mon, 19 Mar 2012 03:37:38 -0400 Received: from zene.cmpxchg.org ([85.214.230.12]:59613 "EHLO zene.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752731Ab2CSHhg (ORCPT ); Mon, 19 Mar 2012 03:37:36 -0400 Date: Mon, 19 Mar 2012 08:37:13 +0100 From: Johannes Weiner To: Fengguang Wu Cc: Andrew Morton , Jan Kara , Greg Thelen , Ying Han , KAMEZAWA Hiroyuki , Rik van Riel , Mel Gorman , Minchan Kim , Linux Memory Management List , LKML Subject: Re: [PATCH] mm: use global_dirty_limit in throttle_vm_writeout() Message-ID: <20120319073713.GC1841@cmpxchg.org> References: <20120302061451.GA6468@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120302061451.GA6468@localhost> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 02, 2012 at 02:14:51PM +0800, Fengguang Wu wrote: > When starting a memory hog task, a desktop box w/o swap is found to go > unresponsive for a long time. It's solely caused by lots of congestion > waits in throttle_vm_writeout(): > > gnome-system-mo-4201 553.073384: congestion_wait: throttle_vm_writeout+0x70/0x7f shrink_mem_cgroup_zone+0x48f/0x4a1 > gnome-system-mo-4201 553.073386: writeback_congestion_wait: usec_timeout=100000 usec_delayed=100000 > gtali-4237 553.080377: congestion_wait: throttle_vm_writeout+0x70/0x7f shrink_mem_cgroup_zone+0x48f/0x4a1 > gtali-4237 553.080378: writeback_congestion_wait: usec_timeout=100000 usec_delayed=100000 > Xorg-3483 553.103375: congestion_wait: throttle_vm_writeout+0x70/0x7f shrink_mem_cgroup_zone+0x48f/0x4a1 > Xorg-3483 553.103377: writeback_congestion_wait: usec_timeout=100000 usec_delayed=100000 > > The root cause is, the dirty threshold is knocked down a lot by the > memory hog task. Fixed by using global_dirty_limit which decreases > gradually on such events and can guarantee we stay above (the also > decreasing) nr_dirty in the progress of following down to the new > dirty threshold. > > Signed-off-by: Fengguang Wu Acked-by: Johannes Weiner