From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id C9B576B0071 for ; Sun, 21 Nov 2010 20:17:50 -0500 (EST) Message-ID: <4CE9C4A9.3040406@redhat.com> Date: Sun, 21 Nov 2010 20:17:29 -0500 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [RFC 1/2] deactive invalidated pages References: In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Minchan Kim Cc: Andrew Morton , linux-mm , LKML , Peter Zijlstra , KOSAKI Motohiro , Johannes Weiner , Nick Piggin List-ID: On 11/21/2010 09:30 AM, Minchan Kim wrote: > Recently, there are reported problem about thrashing. > (http://marc.info/?l=rsync&m=128885034930933&w=2) > It happens by backup workloads(ex, nightly rsync). > That's because the workload makes just use-once pages > and touches pages twice. It promotes the page into > active list so that it results in working set page eviction. > > Some app developer want to support POSIX_FADV_NOREUSE. > But other OSes don't support it, either. > (http://marc.info/?l=linux-mm&m=128928979512086&w=2) > > By Other approach, app developer uses POSIX_FADV_DONTNEED. > But it has a problem. If kernel meets page is writing > during invalidate_mapping_pages, it can't work. > It is very hard for application programmer to use it. > Because they always have to sync data before calling > fadivse(..POSIX_FADV_DONTNEED) to make sure the pages could > be discardable. At last, they can't use deferred write of kernel > so that they could see performance loss. > (http://insights.oetiker.ch/linux/fadvise.html) This looks promising... Acked-by: Rik van Riel -- All rights reversed -- 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/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org