From mboxrd@z Thu Jan 1 00:00:00 1970 From: Samuel Thibault Subject: Re: CPU scheduling of domains and vcpus Date: Mon, 21 Apr 2008 22:34:13 +0100 Message-ID: <20080421213413.GE6127@implementation> References: <1301abeb0804211052i2c498568ue1a761ae8a618029@mail.gmail.com> <20080421175630.GA6127@implementation> <20080421203218.GA14282@silverwood.ncultra.org> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: <20080421203218.GA14282@silverwood.ncultra.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: "Mike D. Day" Cc: Nauman Rafique , xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org Mike D. Day, le Mon 21 Apr 2008 16:32:18 -0400, a écrit : > On 21/04/08 18:56 +0100, Samuel Thibault wrote: > > Nauman Rafique, le Mon 21 Apr 2008 13:52:21 -0400, a écrit : > > > In fact, wasted cycles can probably be avoided by doing opportunisitic > > > gang scheduling (i.e. gang schedule, unless there would be wasted > > > cycles) > > > > How do you detect that there would be wasted cycles? > > The only way is for a very self-aware guest to use a paravirtual > feature to give a hint to the scheduler. Agreed :) > Alternatively, the scheduler can notify the guest that it is about to > be preempted by the hypervisor and now would be a good time to sleep > before gaining a contended spinlock. Mmm, "about to be" means "on the next tick" then. That may be a long time. Samuel