From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 26 Jan 2007 20:44:40 +0000 (GMT) From: Mel Gorman Subject: Re: [PATCH 3/8] Allow huge page allocations to use GFP_HIGH_MOVABLE In-Reply-To: <45BA49F2.2000804@nortel.com> Message-ID: References: <20070125234458.28809.5412.sendpatchset@skynet.skynet.ie> <20070125234558.28809.21103.sendpatchset@skynet.skynet.ie> <45BA49F2.2000804@nortel.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: owner-linux-mm@kvack.org Return-Path: To: Chris Friesen Cc: Christoph Lameter , linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Fri, 26 Jan 2007, Chris Friesen wrote: > Mel Gorman wrote: > >> Worse, the problem is to have high order contiguous blocks free at the time >> of allocation without reclaim or migration. If the allocations were not >> atomic, anti-fragmentation as it is today would be enough. > > Has anyone looked at marking the buffers as "needs refilling" then kick off a > kernel thread or something to do the allocations under GFP_KERNEL? I haven't seen it being discussed although it's probably doable as an addition to the existing mempool mechanism. Anti-fragmentation would mean that the non-atomic GFP_KERNEL allocation had a chance of succeeding. > That way we avoid having to allocate the buffers with GFP_ATOMIC. > Unless the load was so high that the pool was getting depleted and memory under so much pressure that reclaim could not keep up. But yes, it's possible that GFP_ATOMIC allocations could be avoided the majority of times. > I seem to recall that the tulip driver used to do this. Is it just too > complicated from a race condition standpoint? > It shouldn't be that complicated. > We currently see this issue on our systems, as we have older e1000 hardware > with 9KB jumbo frames. After a while we just fail to allocate buffers and > the system goes belly-up. > Can you describe a reliable way of triggering this problem? At best, I hear "on our undescribed workload, we sometimes see this problem" but not much in the way of details. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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