From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pasi =?iso-8859-1?Q?K=E4rkk=E4inen?= Subject: Re: LONG: An Asymmetric-Aware Scheduler for Hypervisor Date: Fri, 26 Aug 2011 22:44:14 +0300 Message-ID: <20110826194414.GN32373@reaktio.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Nilesh Somani Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On Sat, Aug 27, 2011 at 01:05:55AM +0530, Nilesh Somani wrote: > * Topic: *Description on How to make the scheduler of Hypervisor > asymmetric aware. > > The processor's have evolved from single-core to multi-core > processors. But these Processors > have been Symmetric ie identical.Every day the data on web in increasing and > the companies need > to set up large and powerful data center's. The power consumption is thus > increasing to a large extent. > Even as the requests on web increase the number of core's also need to > increased to speed up the > processing in large data center's. But with increasing number of cores the > power consumption is also > increasing. > If the application has less Instruction level parallelism then its > latency on high core processor that > supports high level of parallelism increases with power consumption. So to > deal with these situations > came Asymmetric Multi core Processors. > These are processor's with some fast cores and some slow cores. Now > the application requiring > low ILP can run on slow cores thus reducing the latency and the power > consumption. The area required > for 4 fast cores can have 2 fast cores and 6 small cores. The performance > increase in multithreading > is anytime more on 8 cores(2-fast and 6-slow) rather than 4 fast cores. > What I came up in a paper is that the hypervisor's today are > asymmetric unaware. Thus for every > request it gets it treats all the processor's identical even in asymmetric > hardware. Consider IBM > Blade Server QS series server that has 2 cell processors of 3.2 GHz. This > means there are 2 fast cores > and 16 slow cores compared to the fast ones. It might happen that the > request to hypervisor is for fast > core but suppose both the fast cores are not idle and as the hypervisor > treats all the cores one and the same > it might transfer the request to slow core which is not desired. > So to deal with such situations and to improve the efficiency in > power i propose to modify the scheduler > of the Xen hypervisor and make it asymmetric aware to schedule the jobs > properly ie in a manner to increase > the overall efficiency. Care also needs to be taken that the fast cores dont > go idle before the slow cores to > increase the efficiency and performance. Also there should be fairness among > the jobs requesting fast or > slow cores. We can also assign priorities to VM's such that the requests > from a particular VM goes to either > fast or slow cores. > > I had some doubts regarding this. > I went through some IEEE and ASM papers and there has been proposals to make > schedulers aware of AMPs. So why hasn't it not yet being implemented in Xen? > Are there any issues? > Is there any other hardware other than Cell processor to go on with the > idea? > The first problem is that Xen hasn't been ported to PPC/Cell. (http://wiki.xensource.com/xenwiki/XenPPC) Are there Asymmetric x86/x64 systems out there? -- Pasi