From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752788Ab3FZTj3 (ORCPT ); Wed, 26 Jun 2013 15:39:29 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:54287 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752349Ab3FZTj2 (ORCPT ); Wed, 26 Jun 2013 15:39:28 -0400 Date: Wed, 26 Jun 2013 12:39:25 -0700 From: Andrew Morton To: Mel Gorman Cc: Jiri Slaby , Valdis Kletnieks , Rik van Riel , Zlatko Calusic , Johannes Weiner , dormando , Michal Hocko , Jan Kara , Dave Chinner , Kamezawa Hiroyuki , Linux-FSDevel , Linux-MM , LKML Subject: Re: [PATCH 1/2] mm: vmscan: Avoid direct reclaim scanning at maximum priority Message-Id: <20130626123925.6a15ce3874fa4b0cc8390a0a@linux-foundation.org> In-Reply-To: <1372250364-20640-2-git-send-email-mgorman@suse.de> References: <1372250364-20640-1-git-send-email-mgorman@suse.de> <1372250364-20640-2-git-send-email-mgorman@suse.de> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 26 Jun 2013 13:39:23 +0100 Mel Gorman wrote: > Page reclaim at priority 0 will scan the entire LRU as priority 0 is > considered to be a near OOM condition. Direct reclaim can reach this > priority while still making reclaim progress. This patch avoids > reclaiming at priority 0 unless no reclaim progress was made and > the page allocator would consider firing the OOM killer. The > user-visible impact is that direct reclaim will not easily reach > priority 0 and start swapping prematurely. That's a bandaid. Priority 0 should be a pretty darn rare condition. How often is it occurring, and do you know why?