From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with ESMTP id 6E1816B01F1 for ; Wed, 18 Aug 2010 05:59:08 -0400 (EDT) Subject: Re: [RFC][PATCH] Per file dirty limit throttling From: Peter Zijlstra In-Reply-To: <201008181452.05047.knikanth@suse.de> References: <201008160949.51512.knikanth@suse.de> <201008171039.23701.knikanth@suse.de> <1282033475.1926.2093.camel@laptop> <201008181452.05047.knikanth@suse.de> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Date: Wed, 18 Aug 2010 11:58:56 +0200 Message-ID: <1282125536.1926.3675.camel@laptop> Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org To: Nikanth Karthikesan Cc: Wu Fengguang , Bill Davidsen , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Jens Axboe , Andrew Morton , Jan Kara List-ID: On Wed, 2010-08-18 at 14:52 +0530, Nikanth Karthikesan wrote: > On Tuesday 17 August 2010 13:54:35 Peter Zijlstra wrote: > > On Tue, 2010-08-17 at 10:39 +0530, Nikanth Karthikesan wrote: > > > Oh, nice. Per-task limit is an elegant solution, which should help > > > during most of the common cases. > > > > > > But I just wonder what happens, when > > > 1. The dirtier is multiple co-operating processes > > > 2. Some app like a shell script, that repeatedly calls dd with seek a= nd > > > skip? People do this for data deduplication, sparse skipping etc.. > > > 3. The app dies and comes back again. Like a VM that is rebooted, and > > > continues writing to a disk backed by a file on the host. > > > > > > Do you think, in those cases this might still be useful? > >=20 > > Those cases do indeed defeat the current per-task-limit, however I thin= k > > the solution to that is to limit the amount of writeback done by each > > blocked process. > >=20 >=20 > Blocked on what? Sorry, I do not understand. balance_dirty_pages(), by limiting the work done there (or actually, the amount of page writeback completions you wait for -- starting IO isn't that expensive), you can also affect the time it takes, and therefore influence the impact. -- 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/ . Don't email: email@kvack.org