From mboxrd@z Thu Jan 1 00:00:00 1970 From: Srivatsa Vaddagiri Subject: Re: [PATCH] kvm-vmx: add module parameter to avoid trapping HLT instructions (v2) Date: Fri, 3 Dec 2010 17:27:52 +0530 Message-ID: <20101203115752.GD27994@linux.vnet.ibm.com> References: <1291298357-5695-1-git-send-email-aliguori@us.ibm.com> <20101202191416.GQ10050@sequoia.sous-sol.org> Reply-To: vatsa@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Anthony Liguori , kvm@vger.kernel.org, Avi Kivity , Marcelo Tosatti To: Chris Wright Return-path: Received: from e39.co.us.ibm.com ([32.97.110.160]:47684 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758485Ab0LCL55 (ORCPT ); Fri, 3 Dec 2010 06:57:57 -0500 Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e39.co.us.ibm.com (8.14.4/8.13.1) with ESMTP id oB3BkQKr007114 for ; Fri, 3 Dec 2010 04:46:26 -0700 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay04.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id oB3BvuKT136406 for ; Fri, 3 Dec 2010 04:57:56 -0700 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id oB3Bvtum027991 for ; Fri, 3 Dec 2010 04:57:56 -0700 Content-Disposition: inline In-Reply-To: <20101202191416.GQ10050@sequoia.sous-sol.org> Sender: kvm-owner@vger.kernel.org List-ID: On Thu, Dec 02, 2010 at 11:14:16AM -0800, Chris Wright wrote: > Perhaps it should be a VM level option. And then invert the notion. > Create one idle domain w/out hlt trap. Give that VM a vcpu per pcpu > (pin in place probably). And have that VM do nothing other than hlt. > Then it's always runnable according to scheduler, and can "consume" the > extra work that CFS wants to give away. That's not sufficient. Lets we have 3 guests A, B, C that need to be rate limited to 25% on a single cpu system. We create this idle guest D that is 100% cpu hog as per above definition. Now when one of the guest is idle, what ensures that the idle cycles of A is given only to D and not partly to B/C? - vatsa