From mboxrd@z Thu Jan 1 00:00:00 1970 From: Srivatsa Vaddagiri Subject: Re: [PATCH RFC 2/4] Add yield hypercall for KVM guests Date: Wed, 28 Jul 2010 20:25:16 +0530 Message-ID: <20100728145516.GB27739@linux.vnet.ibm.com> References: <20100726061150.GB21699@linux.vnet.ibm.com> <20100726061445.GB8402@linux.vnet.ibm.com> <4C4DC3AD.7010404@goop.org> Reply-To: vatsa@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: avi@redhat.com, Marcelo Tosatti , Gleb Natapov , linux-kernel@vger.kernel.org, npiggin@suse.de, kvm@vger.kernel.org, bharata@in.ibm.com, Balbir Singh , Jan Beulich To: Jeremy Fitzhardinge Return-path: Content-Disposition: inline In-Reply-To: <4C4DC3AD.7010404@goop.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Mon, Jul 26, 2010 at 10:19:41AM -0700, Jeremy Fitzhardinge wrote: > On 07/25/2010 11:14 PM, Srivatsa Vaddagiri wrote: > >Add KVM hypercall for yielding vcpu timeslice. > > Can you do a directed yield? We don't have that support yet in Linux scheduler. Also I feel it would be more useful when the target vcpu and yielding vcpu are on the same physical cpu, rather than when they are on separate cpus. With latter, yielding (or donating) timeslice need not ensure that target vcpu runs immediately and also I suspect fairness issues needs to be tackled as well (large number of waiters shouldn't boot a lock-holders time slice too much that it gets a larger share). - vatsa