Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932425AbXBTLbn (ORCPT ); Tue, 20 Feb 2007 06:31:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932886AbXBTLbn (ORCPT ); Tue, 20 Feb 2007 06:31:43 -0500 Received: from agminet01.oracle.com ([141.146.126.228]:47217 "EHLO agminet01.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932425AbXBTLbm (ORCPT ); Tue, 20 Feb 2007 06:31:42 -0500 Date: Tue, 20 Feb 2007 06:30:12 -0500 From: Chris Mason To: Miklos Szeredi Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: dirty balancing deadlock Message-ID: <20070220113012.GN6133@think.oraclecorp.com> References: <20070218125307.4103c04a.akpm@linux-foundation.org> <20070218145929.547c21c7.akpm@linux-foundation.org> <20070218155916.0d3c73a9.akpm@linux-foundation.org> <20070220001351.GJ6133@think.oraclecorp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.12-2006-07-14 X-Whitelist: TRUE X-Whitelist: TRUE X-Brightmail-Tracker: AAAAAQAAAAI= Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1589 Lines: 38 On Tue, Feb 20, 2007 at 09:47:11AM +0100, Miklos Szeredi wrote: > > > How about this? > > > > > > Solves the FUSE deadlock, but not the throttle_vm_writeout() one. > > > I'll try to tackle that one as well. > > > > > > If the per-bdi dirty counter goes below 16, balance_dirty_pages() > > > returns. > > > > > > Does the constant need to tunable? If it's too large, then the global > > > threshold is more easily exceeded. If it's too small, then in a tight > > > situation progress will be slower. > > > > Ok, what is supposed to happen here is that filesystems are supposed to > > be throttled from making more dirty pages when the system is over the > > threshold. Even if filesystem A doesn't have much to contribute, and > > filesystem B is the cause of 99% of the dirty pages, the goal of the > > threshold is to prevent more dirty data from happening, and filesystem A > > should block. > > Which is the cause of the current deadlock. But if we allow > filesystem A to go into the red just a little, the deadlock is > avoided, because it can continue to make progress with cleaning the > dirtyness produced by B. > > The maximum that filesystems can go over the limit will be > > (16 + epsilon) * number-of-queues Right, even for thousands of mounted filesystems ~16 pages per FS effectively pinned is not horrible. -chris - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/