From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 20 Feb 2007 06:30:12 -0500 From: Chris Mason 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: Sender: owner-linux-mm@kvack.org Return-Path: To: Miklos Szeredi Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: 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, 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