From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: KVM Test result, kernel 873c05f.., userspace d102d75.. Date: Thu, 24 Apr 2008 16:44:27 +0300 Message-ID: <48108EBB.3050606@qumranet.com> References: <48106140.9070600@intel.com> <481070DF.8070709@qumranet.com> <200804242059.44235.sheng.yang@intel.com> <48108466.2080707@qumranet.com> <4810893C.2050101@qumranet.com> <48108C08.1020706@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel@lists.sourceforge.net, Marcelo Tosatti To: Chris Lalancette Return-path: In-Reply-To: <48108C08.1020706@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces@lists.sourceforge.net Errors-To: kvm-devel-bounces@lists.sourceforge.net List-Id: kvm.vger.kernel.org Chris Lalancette wrote: > Avi Kivity wrote: > >> Ok. __pit_timer_fn() is called from an interrupt, which then calls >> smp_call_function_single(), which calls spin_lock(). If we've already >> taken the lock, we hang. >> >> > > Ah. Just adding a "me too"; I didn't get a chance to debug it yesterday, but I > was seeing similar problems. If I disabled in-kernel pit with -no-kvm-pit, all > was well. > How to fix it, though? the only idea that comes to mind is to affine the hrtimer with vcpu0 (like the local apic timers) which would mean we only need to unwait the waitqueue, and never need to send the IPI. Would slightly improve performance as well. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone