From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 5E6C08D0017 for ; Sun, 14 Nov 2010 00:09:33 -0500 (EST) Received: from m3.gw.fujitsu.co.jp ([10.0.50.73]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id oAE59Vxb020385 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Sun, 14 Nov 2010 14:09:31 +0900 Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 0BE3B45DE4F for ; Sun, 14 Nov 2010 14:09:31 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id D7AE345DE4D for ; Sun, 14 Nov 2010 14:09:30 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id C1C291DB8038 for ; Sun, 14 Nov 2010 14:09:30 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 7E4DC1DB8037 for ; Sun, 14 Nov 2010 14:09:30 +0900 (JST) From: KOSAKI Motohiro Subject: Re: fadvise DONTNEED implementation (or lack thereof) In-Reply-To: <877hgmr72o.fsf@gmail.com> References: <20101109162525.BC87.A69D9226@jp.fujitsu.com> <877hgmr72o.fsf@gmail.com> Message-Id: <20101114140920.E013.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Sun, 14 Nov 2010 14:09:29 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Ben Gamari Cc: kosaki.motohiro@jp.fujitsu.com, linux-kernel@vger.kernel.org, rsync@lists.samba.org, linux-mm@kvack.org List-ID: > On Tue, 9 Nov 2010 16:28:02 +0900 (JST), KOSAKI Motohiro wrote: > > So, I don't think application developers will use fadvise() aggressively > > because we don't have a cross platform agreement of a fadvice behavior. > > > I strongly disagree. For a long time I have been trying to resolve > interactivity issues caused by my rsync-based backup script. Many kernel > developers have said that there is nothing the kernel can do without > more information from user-space (e.g. cgroups, madvise). While cgroups > help, the fix is round-about at best and requires configuration where > really none should be necessary. The easiest solution for everyone > involved would be for rsync to use FADV_DONTNEED. The behavior doesn't > need to be perfectly consistent between platforms for the flag to be > useful so long as each implementation does something sane to help > use-once access patterns. > > People seem to mention frequently that there are no users of > FADV_DONTNEED and therefore we don't need to implement it. It seems like > this is ignoring an obvious catch-22. Currently rsync has no fadvise > support at all, since using[1] the implemented hints to get the desired > effect is far too complicated^M^M^M^Mhacky to be considered > merge-worthy. Considering the number of Google hits returned for > fadvise, I wouldn't be surprised if there were countless other projects > with this same difficulty. We want to be able to tell the kernel about > our useage patterns, but the kernel won't listen. Because we have an alternative solution already. please try memcgroup :) -- 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