From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [PATCH] remove throttle_vm_writeout() From: Trond Myklebust In-Reply-To: <1191612043.6715.139.camel@heimdal.trondhjem.org> References: <20071004145640.18ced770.akpm@linux-foundation.org> <20071004160941.e0c0c7e5.akpm@linux-foundation.org> <20071004164801.d8478727.akpm@linux-foundation.org> <20071004174851.b34a3220.akpm@linux-foundation.org> <1191572520.22357.42.camel@twins> <1191577623.22357.69.camel@twins> <1191581854.22357.85.camel@twins> <1191606600.6715.94.camel@heimdal.trondhjem.org> <1191609139.6210.4.camel@lappy> <1191612043.6715.139.camel@heimdal.trondhjem.org> Content-Type: text/plain Date: Fri, 05 Oct 2007 15:23:16 -0400 Message-Id: <1191612196.6715.142.camel@heimdal.trondhjem.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Peter Zijlstra Cc: Miklos Szeredi , akpm@linux-foundation.org, wfg@mail.ustc.edu.cn, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Fri, 2007-10-05 at 15:20 -0400, Trond Myklebust wrote: > On Fri, 2007-10-05 at 20:32 +0200, Peter Zijlstra wrote: > > Well, the thing is, we throttle pageout in throttle_vm_writeout(). As it > > stand we can deadlock there because it just waits for the numbers to > > drop, and unstable pages don't automagically dissapear. Only > > write_inodes() - normally called from balance_dirty_pages() will call > > COMMIT. > > > > So my thought was that calling pageout() on an unstable page would do > > the COMMIT - we're low on memory, otherwise we would not be paging, so > > getting rid of unstable pages seems to make sense to me. > > Why not rather track which mappings have large numbers of outstanding > unstable writes at the VM level, and then add some form of callback to > allow it to notify the filesystem when it needs to flush them out? > > Cheers > Trond BTW: Please note that at least in the case of NFS, you will have to allow for the fact that the filesystem may not be _able_ to cause the numbers to drop. If the server is unavailable, then we're may be stuck in unstable page limbo for quite some time. Trond -- 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