Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1581297

Re: [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX operation is on

From Alexander Shishkin <alexander.shishkin@linux.intel.com>
Newsgroups linux.kernel
Subject Re: [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX operation is on
Date 2017-02-15 14:10 +0100
Message-ID <tb7vk-nR-19@gated-at.bofh.it> (permalink)
References <taLl8-2pq-17@gated-at.bofh.it> <taLuN-2sF-3@gated-at.bofh.it> <taPoK-4Ol-15@gated-at.bofh.it> <tb3i2-5YV-11@gated-at.bofh.it> <tb3Bn-678-13@gated-at.bofh.it>
Organization linux.* mail to news gateway

Show all headers | View raw

Peter Zijlstra <peterz@infradead.org> writes:

> On Wed, Feb 15, 2017 at 10:34:58AM +0200, Alexander Shishkin wrote:
>
>> Well, we can't make the limitation go away. You'll still have to stop
>> kvms to get any 'meaningful' PT data.
>
> Why would you need to stop all VMs in order to get your !VM data? Sure,
> you get black holes where the VM runs, but we should be able to see
> everything else.

No, what I mean is that if you run kvm prior to starting perf record,
which I assume is the case for acme, your entire session is a black
hole. The VMXON happens pretty early on, you can open /dev/kvm,
ioctl(KVM_CREATE_VM) on it and that will do a VMXON already.

The problem is that PT (on BDW) doesn't trace inside VM root mode, not
just between VM entry/VM exit.

Regards,
--
Alex

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 0/2] perf/x86/intel/pt: VMX related updates Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-02-14 14:30 +0100
  [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX operation is on Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-02-14 14:40 +0100
    Re: [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX  operation is on Peter Zijlstra <peterz@infradead.org> - 2017-02-14 15:10 +0100
    Re: [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX  operation is on Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-02-14 18:50 +0100
      Re: [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX operation is on Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-02-15 09:40 +0100
        Re: [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX  operation is on Peter Zijlstra <peterz@infradead.org> - 2017-02-15 10:00 +0100
          Re: [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX operation is on Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-02-15 14:10 +0100
            Re: [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX  operation is on Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-02-15 14:20 +0100
            Re: [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX  operation is on Peter Zijlstra <peterz@infradead.org> - 2017-02-15 14:40 +0100
        Re: [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX  operation is on Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-02-15 14:00 +0100
          Re: [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX operation is on Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-02-15 14:10 +0100
            Re: [PATCH 2/2] perf/x86/intel/pt: Fail event creation if VMX  operation is on Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-02-15 14:20 +0100
  [PATCH 1/2] perf/x86/intel/pt: Fail event scheduling on conflict with VMX Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-02-14 14:40 +0100
    Re: [PATCH 1/2] perf/x86/intel/pt: Fail event scheduling on conflict  with VMX Peter Zijlstra <peterz@infradead.org> - 2017-02-14 15:00 +0100
      Re: [PATCH 1/2] perf/x86/intel/pt: Fail event scheduling on conflict with VMX Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-02-14 17:20 +0100
        Re: [PATCH 1/2] perf/x86/intel/pt: Fail event scheduling on conflict  with VMX Peter Zijlstra <peterz@infradead.org> - 2017-02-14 17:30 +0100
          Re: [PATCH 1/2] perf/x86/intel/pt: Fail event scheduling on conflict with VMX Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-02-14 18:30 +0100
            Re: [PATCH 1/2] perf/x86/intel/pt: Fail event scheduling on conflict  with VMX Peter Zijlstra <peterz@infradead.org> - 2017-02-14 19:40 +0100
              Re: [PATCH 1/2] perf/x86/intel/pt: Fail event scheduling on conflict  with VMX Peter Zijlstra <peterz@infradead.org> - 2017-02-14 20:50 +0100
                Re: [PATCH 1/2] perf/x86/intel/pt: Fail event scheduling on conflict with VMX Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2017-02-15 09:20 +0100
                Re: [PATCH 1/2] perf/x86/intel/pt: Fail event scheduling on conflict  with VMX Peter Zijlstra <peterz@infradead.org> - 2017-02-15 10:00 +0100

csiph-web