From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 0/7] KVM: Suspend and cpu hotplug fixes Date: Sun, 27 May 2007 13:20:47 +0300 Message-ID: <46595B7F.9030006@qumranet.com> References: <1180008615579-git-send-email-avi@qumranet.com> <1180055432.9919.3.camel@sli10-conroe.sh.intel.com> <46569E23.6010101@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, lhcs-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Shaohua Li Return-path: In-Reply-To: <46569E23.6010101-atKUWr5tajBWk0Htik3J/w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Avi Kivity wrote: > I estimate that that take_cpu_down will run for about a millisecond if > there are a few hundred vcpus which have last run on the dying cpu (and > that's an extreme case, which is not expected in normal operation). I measured vmclear time on an uncached vmcs (which would be all except for a handful which are cached on the cpu core) at 144 cycles. Assuming a couple of cache misses for walking the list and accessing the vmcs, we're at about 500 cycles per vcpu, or 250us @ 2GHz. So worst case is significantly less than 1 ms. Is this acceptable for take_cpu_down()? -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/