From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Dunlap Subject: Re: Question about the ability of credit scheduler to handle I/O and CPU intensive VMs Date: Mon, 18 Oct 2010 11:25:42 +0100 Message-ID: <4CBC20A6.4030809@eu.citrix.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: 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: Yuehai Xu Cc: "xen-devel@lists.xensource.com" , "yhxu@wayne.edu" List-Id: xen-devel@lists.xenproject.org I think this is probably an area open for research. :-) I would think 500us or 1ms would be decent options, but that's mostly a guess. -George On 12/10/10 13:42, Yuehai Xu wrote: > Sorry for making noise, the mode is PV. Because my scheduler is set to > CPU fairness only, so the number I calculated is almost the same, as > long as I set it to I/O favor, the number is different. > > Here is another question, since we always say a short period of time, > how long it should be? 500us? 50us? 1ms? is there any hint that I can > follow? > > Thanks, > Yuehai > > >> >> Remind me, are you running in HVM mode, or PV mode? >> >> That sounds unusual. Is it the number of events delivered, or the >> number of times the guest woke up? NB they're not the same -- an HVM >> guest will block and then wake up on the completion of an I/O >> instruction which is handled by qemu. >> >> If you're running in HVM mode, you can use "xenalyze -s" will give you >> a summary of the trace. In the summary you can see not only now many >> times a VM woke up, but which interrupt was delivered how many times. >> >> At the moment, from Xen's perspective, an event delivery is an event >> delivery. You'd have to manually add some way of classifying an event >> as "I/O". >> >> -George >>