From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: page swap allocation error/failure in 2.6.25 From: Peter Zijlstra In-Reply-To: <20080727060701.GA7157@samad.com.au> References: <20080725072015.GA17688@samad.com.au> <1216971601.7257.345.camel@twins> <20080727060701.GA7157@samad.com.au> Content-Type: text/plain Date: Mon, 28 Jul 2008 12:04:47 +0200 Message-Id: <1217239487.6331.24.camel@twins> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Alex Samad Cc: linux-kernel@vger.kernel.org, linux-mm , Mel Gorman List-ID: On Sun, 2008-07-27 at 16:07 +1000, Alex Samad wrote: > On Fri, Jul 25, 2008 at 09:40:01AM +0200, Peter Zijlstra wrote: > > On Fri, 2008-07-25 at 17:20 +1000, Alex Samad wrote: > > > Hi > > [snip] > > > > > > > Its harmless if it happens sporadically. > > > > Atomic order 2 allocations are just bound to go wrong under pressure. > can you point me to any doco that explains this ? An order 2 allocation means allocating 1<<2 or 4 physically contiguous pages. Atomic allocation means not being able to sleep. Now if the free page lists don't have any order 2 pages available due to fragmentation there is currently nothing we can do about it. I've been meaning to try and play with 'atomic' page migration to try and assemble a higher order page on demand with something like memory compaction. But its never managed to get high enough on the todo list.. -- 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