From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Stevens Subject: Re: KVM and the OOM-Killer Date: Thu, 13 May 2010 14:39:45 +0100 Message-ID: <4BEC0121.2020700@jrcs.co.uk> References: <4BEBEE8F.9050508@jrcs.co.uk> <4BEBF2F8.7020507@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: Avi Kivity , kvm@vger.kernel.org Return-path: Received: from mk-outboundfilter-6-a-2.mail.uk.tiscali.com ([212.74.114.16]:37026 "EHLO mk-outboundfilter-6-a-2.mail.uk.tiscali.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752552Ab0EMNjr (ORCPT ); Thu, 13 May 2010 09:39:47 -0400 In-Reply-To: <4BEBF2F8.7020507@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: > I'd go with 64-bit at 2GB and above. It's both faster and safer. safer, how? (apart from no lowmem exhaust). On a different subject, the qemu documentation says a guest VM can only have 2Gb of memory - does this still apply when using a 64bit host O/S ? > The lowmem load is about 0.5% of guest memory, so 48GB means 240MB > lowmem allocated. Thin ice. We currently only have about 12Gb used by the VM guests, so not hitting that issue - the rest of HIGHMEM is host disk cache. Our experience is that the bottle-neck on number of VM guests is disk i/o - with loads of memory we've pretty much eliminated reads, so that means disk writes. > Since you can run a 64-bit kernel with your existing userspace, at least > you have a simple upgrade path. Not sure I like the idea of running a 64bit user space kernel on top of a 32bit host, prefer to re-install. Can I just replace my kernel with a 64bit one, or do I have to re-install the host O/S ? James