From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: performance specs on VT-x vmenter/exit Date: Thu, 06 Dec 2007 13:56:16 -0600 Message-ID: <475853E0.7080005@codemonkey.ws> References: <47584142.10600@qumranet.com> <4758442B.8060401@codemonkey.ws> <47584832.9010708@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, Dan To: Avi Kivity Return-path: In-Reply-To: <47584832.9010708-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: > Anthony Liguori wrote: >>> >>> >>> Have a look at user/test/x86/vmexit.c, which does exactly that. >>> >>> >> >> That only gives you the combined count of a vmenter and vmexit. > > Right; furthermore it measures kvm overhead and not just instruction > latency. True. Also, I don't know what Dan is looking to measure, but the cost of vmexits will varying depending on the reason for exit. vmexit.c uses cpuid() which I suspect is slower than vmexit or pio but faster than pf. It would be interesting to measure the individual exit reasons. Regards, Anthony Liguori ------------------------------------------------------------------------- SF.Net email is sponsored by: Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://sourceforge.net/services/buy/index.php