From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juergen Gross Subject: Re: RE: The caculation of the credit in credit_scheduler Date: Wed, 10 Nov 2010 06:46:16 +0100 Message-ID: <4CDA31A8.4050308@ts.fujitsu.com> References: <789F9655DD1B8F43B48D77C5D30659732FD0A5C9@shsmsx501.ccr.corp.intel.com> <4CD95A22.2090902@eu.citrix.com> <789F9655DD1B8F43B48D77C5D30659732FD7DF70@shsmsx501.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <789F9655DD1B8F43B48D77C5D30659732FD7DF70@shsmsx501.ccr.corp.intel.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: "Jiang, Yunhong" Cc: George Dunlap , "xen-devel@lists.xensource.com" , "Dong, Eddie" , "Zhang, Xiantao" List-Id: xen-devel@lists.xenproject.org On 11/10/10 03:39, Jiang, Yunhong wrote: > > >> -----Original Message----- >> From: George Dunlap [mailto:George.Dunlap@eu.citrix.com] >> Sent: Tuesday, November 09, 2010 10:27 PM >> To: Jiang, Yunhong >> Cc: xen-devel@lists.xensource.com; Dong, Eddie; Zhang, Xiantao >> Subject: Re: The caculation of the credit in credit_scheduler >> >> On 05/11/10 07:06, Jiang, Yunhong wrote: >>> The reason is how the credit is caculated. Although the 3 HVM domains is pinned >> to 2 PCPU and share the 2 CPUs, they will all get 2* 300 credit when credit account. >> That means the I/O intensive HVM domain will never be under credit, thus it will >> preempt the CPU intensive whenever it is boost (i.e. after I/O access to QEMU), and >> it is set to be TS_UNDER only at the tick time, and then, boost again. >> >> I suspect that the real reason you're having trouble is that pinning and >> the credit mechanism don't work very well together. Instead of pinning, >> have you tried using the cpupools interface to make a 2-cpu pool to put >> the VMs into? That should allow the credit to be divided appropriately. > > I have a quick look in the code, and seems the cpu pool should not help on such situation. The CPU poll only cares about the CPUs a domain can be scheduled, but not about the credit caculation. With cpupools you avoid the pinning. This will result in better credit calculation results. Juergen -- Juergen Gross Principal Developer Operating Systems TSP ES&S SWE OS6 Telephone: +49 (0) 89 3222 2967 Fujitsu Technology Solutions e-mail: juergen.gross@ts.fujitsu.com Domagkstr. 28 Internet: ts.fujitsu.com D-80807 Muenchen Company details: ts.fujitsu.com/imprint.html