I really appreciate for your answers. Last but not the least, I want to make it more clear:
> The hypervisor will provide dom0 with a raw sample (guest's, dom0's or > hypervisor's) and then it's the job of dom0 kernel to properly tag and > format it and make it available to the userland (i.e. perf itself). Does this mean if I run the perf command on Dom0 while other domains are running, we can collect the performance counter values without distinguishing each domain, right? > The tool will then look at the tag and display the event as belonging to > host (dom0, really) or guest. This is supported for KVM, with 'perf kvm' > commands. > > So if you can run perf kvm commands then you may be able to > differentiate dom0's and guest's samples (you will also see hypervisor > samples but they won't get resolved to symbols). I am just not sure per > kvm will run on a non-KVM host. I had a private copy where it did but > this was based on a fairly old version of Linux. > > (Also, stack profiling is not supported at all). I wonder if you can share the private copy of your code. I’m looking into the source code of the patches, and it seems there’s a way to do it. Even if your codes are outdated, I think I can manage to port it. I will promise once I finish the porting, I will share my adjustment of your code as well. Best, Sanghyun. > On Aug 29, 2016, at 5:24 PM, Boris Ostrovsky <boris.ostrov...@oracle.com> > wrote: > > On 08/29/2016 05:08 PM, Sanghyun Hong wrote: >>> Yes, this will allow the hypervisor to collect samples from multiple >>> guests. However, the tool (perf) probably won't be able to properly >>> process these samples. But you can try. >> >> I understand, thus, I applied the patches and set >> the /pmu_mode/ to *all*. However, I’m really curious what you mean by >> the tool (*perf*) probably won’t be able to properly process these >> samples. Is there any things I have to have in mind while collecting >> the counters, or will it have incorrect values of the counters? > > The hypervisor will provide dom0 with a raw sample (guest's, dom0's or > hypervisor's) and then it's the job of dom0 kernel to properly tag and > format it and make it available to the userland (i.e. perf itself). The > tool will then look at the tag and display the event as belonging to > host (dom0, really) or guest. This is supported for KVM, with 'perf kvm' > commands. > > So if you can run perf kvm commands then you may be able to > differentiate dom0's and guest's samples (you will also see hypervisor > samples but they won't get resolved to symbols). I am just not sure per > kvm will run on a non-KVM host. I had a private copy where it did but > this was based on a fairly old version of Linux. > > (Also, stack profiling is not supported at all). > >> >>> You will want to run dom0 on all physical processors (i.e. no >>> dom0_max_vcpus boot option) and pin all VCPUs for both dom0 and the >>> guest. >> >> Sure, thanks! My machine has four physical cores, and I’ve set >> the /dom0_max_vcpus=4/. I think it will have the same effect in >> removing the /dom0_max_vcpus/ option. > > Yes. > > -boris > >> >> Best, >> Sanghyun. >> >> >>> On Aug 29, 2016, at 4:59 PM, Boris Ostrovsky >>> <boris.ostrov...@oracle.com <mailto:boris.ostrov...@oracle.com>> wrote: >>> >>> On 08/29/2016 02:42 PM, Sanghyun Hong wrote: >>>> Hi Boris, >>>> >>>> I’ve found the >>>> documentations(https://github.com/torvalds/linux/blob/master/Documentation/ABI/testing/sysfs-hypervisor-pmu) >>>> in the kernel source code, and it seems like if we change the mode >>>> from *self* to *all* then we can collect counters for all the domains, >>>> right? >>> >>> Yes, this will allow the hypervisor to collect samples from multiple >>> guests. However, the tool (perf) probably won't be able to properly >>> process these samples. But you can try. >>> >>> You will want to run dom0 on all physical processors (i.e. no >>> dom0_max_vcpus boot option) and pin all VCPUs for both dom0 and the >>> guest. >>> >>> >>> -boris >>> >>>> >>>> All the best, >>>> Sanghyun. >>>> >>>> >>>>> On Aug 29, 2016, at 12:36 PM, Boris Ostrovsky >>>>> <boris.ostrov...@oracle.com <mailto:boris.ostrov...@oracle.com> >>>>> <mailto:boris.ostrov...@oracle.com>> wrote: >>>>> >>>>> On 08/29/2016 09:18 AM, Sanghyun Hong wrote: >>>>>> Dear Xen-Devel Community: >>>>>> >>>>>> I’m a grad student working on measuring performance counters at the >>>>>> Xen domains. I read this >>>>>> thread(https://wiki.xenproject.org/wiki/Xen_Profiling:_oprofile_and_perf) >>>>>> in >>>>>> web, and it says using Linux perf command will let us collecting >>>>>> performance counters in both dom0 and domU. Does it mean that we can >>>>>> collect both of them at once if we run perf command on the dom0? (If >>>>>> not, does it mean we can collect counters for each domain separately >>>>>> once we run the perf command in each domain? >>>>> >>>>> Profiling both guest and dom0 (and the hypervisor) requires changes to >>>>> perf and those are not there yet. >>>>> >>>>> But you can run perf in each guest (including dom0) separately. Make >>>>> sure you have vpmu=true boot option. >>>>> >>>>> -boris >>>>> >>>>> >>>>> >>>>> >>>>> >>>> >>> >>> >> > > _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
