From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 4/5] KVM: Add hypercall queue for paravirt_ops implementation Date: Mon, 18 Jun 2007 16:35:59 +0300 Message-ID: <46768A3F.2010202@qumranet.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <46768724.3000509-rdkfGonbjUSkNkDKm+mE6A@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: Anthony Liguori Cc: kvm-devel , virtualization List-Id: virtualization@lists.linuxfoundation.org Anthony Liguori wrote: >> >> I did, but using kbuild (a simple 'make' with defconfig), not >> kernbench. I get (elapsed time) 308 sec for kvm and 243 sec for native. > > kernbench is a little different. It does a find over the kernel > source tree to attempt to get as much of the kernel in the page cache > as possible. It also uses -j4 by default. > >> >> 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. For every vmexit, it does the entire thing, including vmload/vmsave, fpu switch (if needed), segment reloading, and msr reloading. 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. -- 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/