From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andre Przywara Subject: Re: [PATCH 2 of 4 v7/leftover] libxl: enable automatic placement of guests on NUMA nodes Date: Thu, 26 Jul 2012 14:03:43 +0200 Message-ID: <5011321F.6080601@amd.com> References: <6dab5496964de0830f1a.1343140929@Solace> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <6dab5496964de0830f1a.1343140929@Solace> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Dario Faggioli Cc: Ian Campbell , Stefano Stabellini , George Dunlap , Juergen Gross , Ian Jackson , xen-devel , Roger Pau Monne List-Id: xen-devel@lists.xenproject.org On 07/24/2012 04:42 PM, Dario Faggioli wrote: > If a domain does not have a VCPU affinity, try to pin it automatically > to some PCPUs. This is done taking into account the NUMA characteristics > of the host. In fact, we look for a combination of host's NUMA nodes > with enough free memory and number of PCPUs for the new domain, and pin > it to the VCPUs of those nodes. I have tested this version 7 on my box in various configurations: 1. Homogeneous memory distribution: 8 nodes, each 16 GB 2. "Odd" configuration: 8 nodes, 4 have 8 GB, 4 have 16 GB 3 Flat memory (by using cpus="all") I created up to 32 guests with 2 VCPUs and 2 GB each and observed the distribution after every 8th guest. Another round with 2 VCPU guests, but this time with memory sizes varying from 512MB to 5120MB. The placement was running well in all cases. The only thing I saw as a little sub-optimal placement in the odd configuration (2) with the differently sized guests. This is probably a side effect of Dom0 ballooning, which is not really NUMA aware AFAIK. This leads to a situation, where some nodes just by chance have less memory than a certain guest needs and so are not considered candidates. I think we can perfectly tolerate this behavior for now. I didn't see anything strange with config 1. So this patch gets my: Tested-by: Andre Przywara Please apply to 4.2-unstable! Regards, Andre.