Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752209Ab1FYVlN (ORCPT ); Sat, 25 Jun 2011 17:41:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:24239 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751731Ab1FYVlL (ORCPT ); Sat, 25 Jun 2011 17:41:11 -0400 Message-ID: <4E0655C8.7080908@redhat.com> Date: Sat, 25 Jun 2011 17:40:24 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110428 Fedora/3.1.10-1.fc15 Lightning/1.0b3pre Thunderbird/3.1.10 MIME-Version: 1.0 To: Mel Gorman CC: Andrew Morton , =?UTF-8?B?UMOhZHJhaWcgQnJh?= =?UTF-8?B?ZHk=?= , James Bottomley , Colin King , Minchan Kim , Andrew Lutomirski , Johannes Weiner , linux-mm , linux-kernel Subject: Re: [PATCH 2/4] mm: vmscan: Do not apply pressure to slab if we are not applying pressure to zone References: <1308926697-22475-1-git-send-email-mgorman@suse.de> <1308926697-22475-3-git-send-email-mgorman@suse.de> In-Reply-To: <1308926697-22475-3-git-send-email-mgorman@suse.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1330 Lines: 30 On 06/24/2011 10:44 AM, Mel Gorman wrote: > During allocator-intensive workloads, kswapd will be woken frequently > causing free memory to oscillate between the high and min watermark. > This is expected behaviour. > > When kswapd applies pressure to zones during node balancing, it checks > if the zone is above a high+balance_gap threshold. If it is, it does > not apply pressure but it unconditionally shrinks slab on a global > basis which is excessive. In the event kswapd is being kept awake due to > a high small unreclaimable zone, it skips zone shrinking but still > calls shrink_slab(). > > Once pressure has been applied, the check for zone being unreclaimable > is being made before the check is made if all_unreclaimable should be > set. This miss of unreclaimable can cause has_under_min_watermark_zone > to be set due to an unreclaimable zone preventing kswapd backing off > on congestion_wait(). > > Reported-and-tested-by: Pádraig Brady > Signed-off-by: Mel Gorman Acked-by: Rik van Riel -- All rights reversed -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/