From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Stodden Subject: Re: OOM problems Date: Sun, 14 Nov 2010 01:53:06 -0800 Message-ID: <1289728386.11857.22.camel@ramone> References: <4CDE44E2.2060807@nuclearfallout.net> <4FA716B1526C7C4DB0375C6DADBC4EA38D80702C25@LONPMAILBOX01.citrite.net> <4CDE4C08.70309@nuclearfallout.net> <4FA716B1526C7C4DB0375C6DADBC4EA38D80702C2E@LONPMAILBOX01.citrite.net> <4CDE6639.2070509@nuclearfallout.net> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4CDE6639.2070509@nuclearfallout.net> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: John Weekes Cc: Ian Pratt , "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org On Sat, 2010-11-13 at 05:19 -0500, John Weekes wrote: > On 11/13/2010 1:13 AM, Ian Pratt wrote: > > Ah, if you're using loop it may be that you're just filling memory > with dirty pages. Older kernels certainly did this, not sure about newer > ones. > > I'd be inclined to use blktap2 in raw file mode, with "aio:". > > With blktap2, is free RAM in dom0 still used for a disk cache at all? I > have this dom0 set to 1.5 GB mainly to help with caching; if that RAM is > not needed, I'll retool it down to a smaller number. If you're not using cloned images deriving from a shared parent image, that caching won't buy anyone much. Memory better spent on the guests themselves then, thereby their own caches. Keep an eye on /proc/meminfo, it largely depends on number/type of guests, but probably safe to reassign ~800M straight away. blktap2 with aio will move the datapath to direct I/O. Comparend to buffered loops, there's also some notable benefit to crash consistency resulting from that. Daniel