From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 21 Aug 2007 02:32:12 +0200 From: Nick Piggin Subject: Re: [RFC 0/3] Recursive reclaim (on __PF_MEMALLOC) Message-ID: <20070821003212.GC8414@wotan.suse.de> References: <20070814142103.204771292@sgi.com> <20070815122253.GA15268@wotan.suse.de> <1187183526.6114.45.camel@twins> <20070816032921.GA32197@wotan.suse.de> <1187581894.6114.169.camel@twins> 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: Christoph Lameter Cc: Peter Zijlstra , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, dkegel@google.com, David Miller , Daniel Phillips List-ID: On Mon, Aug 20, 2007 at 12:15:01PM -0700, Christoph Lameter wrote: > On Mon, 20 Aug 2007, Peter Zijlstra wrote: > > > > > <> What Christoph is proposing is doing recursive reclaim and not > > > > initiating writeout. This will only work _IFF_ there are clean pages > > > > about. Which in the general case need not be true (memory might be > > > > packed with anonymous pages - consider an MPI cluster doing computation > > > > stuff). So this gets us a workload dependant solution - which IMHO is > > > > bad! > > > > > > Although you will quite likely have at least a couple of MB worth of > > > clean program text. The important part of recursive reclaim is that it > > > doesn't so easily allow reclaim to blow all memory reserves (including > > > interrupt context). Sure you still have theoretical deadlocks, but if > > > I understand correctly, they are going to be lessened. I would be > > > really interested to see if even just these recursive reclaim patches > > > eliminate the problem in practice. > > > > were we much bothered by the buffered write deadlock? - why accept a > > known deadlock if a solid solution is quite attainable? > > Buffered write deadlock? How does that exactly occur? Memory allocation in > the writeout path while we hold locks? Different topic. Peter was talking about the write(2) write deadlock where we take a page fault while holding a page lock (which leads to lock inversion, taking the lock twice etc.) -- 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