From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id 682A56B0087 for ; Tue, 23 Nov 2010 09:57:41 -0500 (EST) Received: by qyk4 with SMTP id 4so1653951qyk.14 for ; Tue, 23 Nov 2010 06:57:39 -0800 (PST) From: Ben Gamari Subject: Re: [RFC 1/2] deactive invalidated pages In-Reply-To: <20101122143817.E242.A69D9226@jp.fujitsu.com> References: <20101122143817.E242.A69D9226@jp.fujitsu.com> Date: Tue, 23 Nov 2010 09:57:35 -0500 Message-ID: <87hbf89jfk.fsf@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro , Minchan Kim Cc: Andrew Morton , linux-mm , LKML , Peter Zijlstra , Rik van Riel , Johannes Weiner , Nick Piggin List-ID: On Tue, 23 Nov 2010 16:16:55 +0900 (JST), KOSAKI Motohiro wrote: > > 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) > > If rsync use the above url patch, we don't need your patch. > fdatasync() + POSIX_FADV_DONTNEED should work fine. > This is quite true, but the patch itself is fairly invasive and unnecessarily so which makes it unsuitable for merging in the eyes of the rsync maintainers (not that I can blame them). This is by no fault of its author; using fadvise is just far harder than it should be. - Ben -- 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