From: David Rientjes Subject: Re: [PATCH 2/4] mm: slub: Do not wake kswapd for SLUBs speculative high-order allocations Date: Mon, 16 May 2011 14:10:24 -0700 (PDT) Message-ID: References: <1305295404-12129-1-git-send-email-mgorman@suse.de> <1305295404-12129-3-git-send-email-mgorman@suse.de> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Andrew Morton , James Bottomley , Colin King , Raghavendra D Prabhu , Jan Kara , Chris Mason , Christoph Lameter , Pekka Enberg , Rik van Riel , Johannes Weiner , linux-fsdevel , linux-mm , linux-kernel , linux-ext4 To: Mel Gorman Return-path: Received: from smtp-out.google.com ([216.239.44.51]:47428 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752238Ab1EPVK2 (ORCPT ); Mon, 16 May 2011 17:10:28 -0400 Received: from wpaz24.hot.corp.google.com (wpaz24.hot.corp.google.com [172.24.198.88]) by smtp-out.google.com with ESMTP id p4GLASfj026594 for ; Mon, 16 May 2011 14:10:28 -0700 Received: from pwi8 (pwi8.prod.google.com [10.241.219.8]) by wpaz24.hot.corp.google.com with ESMTP id p4GLAQ6o012779 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=NOT) for ; Mon, 16 May 2011 14:10:27 -0700 Received: by pwi8 with SMTP id 8so2721078pwi.36 for ; Mon, 16 May 2011 14:10:26 -0700 (PDT) In-Reply-To: <1305295404-12129-3-git-send-email-mgorman@suse.de> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Fri, 13 May 2011, Mel Gorman wrote: > To avoid locking and per-cpu overhead, SLUB optimisically uses > high-order allocations and falls back to lower allocations if they > fail. However, by simply trying to allocate, kswapd is woken up to > start reclaiming at that order. On a desktop system, two users report > that the system is getting locked up with kswapd using large amounts > of CPU. Using SLAB instead of SLUB made this problem go away. > > This patch prevents kswapd being woken up for high-order allocations. > Testing indicated that with this patch applied, the system was much > harder to hang and even when it did, it eventually recovered. > > Signed-off-by: Mel Gorman Acked-by: David Rientjes