From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [PATCH 4/5] KVM: Add hypercall queue for paravirt_ops implementation Date: Mon, 18 Jun 2007 09:02:03 -0500 Message-ID: <4676905B.6000805@codemonkey.ws> References: <4675F462.1010708@codemonkey.ws> <4675F568.90608@codemonkey.ws> <46764B47.5060403@qumranet.com> <46767D47.1010104@codemonkey.ws> <46767F98.70109@qumranet.com> <46768724.3000509@codemonkey.ws> <46768A3F.2010202@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <46768A3F.2010202-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 To: Avi Kivity Cc: kvm-devel , virtualization List-Id: virtualization@lists.linuxfoundation.org Avi Kivity wrote: >>> These numbers are pretty bad. I'd like to improve them, even >>> without PV. >> >> I agree. Do you know what's missing at this point? There isn't a >> whole lot of state saving going on for the light weight exit paths >> for SVM. > > The SVM code doesn't even have a lightweight vmexit path. Sure it does. Quite a lot is deferred to vcpu_{load,put}. > For every vmexit, it does the entire thing, including vmload/vmsave I haven't had a lot of luck eliminating vmload/vmsave. > , fpu switch (if needed) The FPU switch can really be avoided? Is it safe to assume that the KVM code isn't going to use any FPU operations? > , segment reloading, and msr reloading. Yeah, the VMX path is doing some clever things there. A fair bit more could be deferred on SVM. > It could use a lot of work. > > For kbuild vs. kernbench, I suspect that -j4 causes the shadow page > table cache to thrash. 1024 pages may be enough for a single instance > but not -j4. Hopefully replacing the eviction algorithm (currently > FIFO) will help. Otherwise we'll need to resize the cache again. I naively tried to bump it to 2048 and hit a kmalloc limitation. Regards, Anthony Liguori ------------------------------------------------------------------------- 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/