From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH V3] perf & kvm: Enhance perf to collect KVM guest os statistics from host side Date: Wed, 14 Apr 2010 12:57:50 +0300 Message-ID: <4BC5919E.1010400@redhat.com> References: <1902387910.2078.435.camel@ymzhang.sh.intel.com> <4BC588CF.5010507@redhat.com> <201004141743.32393.sheng@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: "Zhang, Yanmin" , Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Marcelo Tosatti , oerg Roedel , Jes Sorensen , Gleb Natapov , Zachary Amsden , zhiteng.huang@intel.com, tim.c.chen@intel.com, Arnaldo Carvalho de Melo To: Sheng Yang Return-path: In-Reply-To: <201004141743.32393.sheng@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 04/14/2010 12:43 PM, Sheng Yang wrote: > On Wednesday 14 April 2010 17:20:15 Avi Kivity wrote: > >> On 04/14/2030 12:05 PM, Zhang, Yanmin wrote: >> >>> Here is the new patch of V3 against tip/master of April 13th >>> if anyone wants to try it. >>> >> Thanks for persisting despite the flames. >> >> Can you please separate arch/x86/kvm part of the patch? That will make >> for easier reviewing, and will need to go through separate trees. >> >> Sheng, did you make any progress with the NMI injection issue? >> > Yes, though some other works interrupt me lately... > > The very first version has issue due to SELF_IPI mode can't be used to send > NMI according to SDM. That's the reason why x2apic don't have way to do this. > Yes, I see that now. Looks like others have the same questions... > But later I found another issue of fail to inspect inside the guest. I think > it's due to NMI is asynchronous event, though it should be triggered very > quickly, you can't guarantee that the handler would be triggered before the > state(current_vcpu) is cleared with current code. > > Maybe just extended the "guest state" region would be fine, if the latency is > stable enough(though I think it maybe platform depended). I am working on this > now. > I wouldn't like to depend on model specific behaviour. One option is to read all the information synchronously and store it in a per-cpu area with atomic instructions, then queue the NMI. Another option is to have another callback which tells us that the NMI is done, and have a busy loop wait until the NMI is delivered. -- error compiling committee.c: too many arguments to function