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Re: [PATCH 1/2] perf/x86/intel/pt: Fail event scheduling on conflict with VMX

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [PATCH 1/2] perf/x86/intel/pt: Fail event scheduling on conflict with VMX
Date 2017-02-14 19:40 +0100
Message-ID <taQb8-5kY-3@gated-at.bofh.it> (permalink)
References (1 earlier) <taLuO-2sF-9@gated-at.bofh.it> <taLOa-2zE-7@gated-at.bofh.it> <taNZE-44x-35@gated-at.bofh.it> <taO9j-47Q-15@gated-at.bofh.it> <taP5o-4Hf-17@gated-at.bofh.it>
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On Tue, Feb 14, 2017 at 07:21:34PM +0200, Alexander Shishkin wrote:
> Peter Zijlstra <peterz@infradead.org> writes:
> 
> > On Tue, Feb 14, 2017 at 06:17:30PM +0200, Alexander Shishkin wrote:
> >> This is called by pmu::add(), which checks hw.state afterwards and if it
> >> finds HES_STOPPED, it returns an error, which event_sched_in() captures
> >> and keeps the event in INACTIVE state. Should I add a comment about it?
> >
> > Egads... so what if ->add() succeeds but we then hit this on
> > ->stop()/->start() due to throttle or period adjust?
> 
> It will hang there with hw.state==PERF_HES_STOPPED till the next
> sched_out. But that will be the case anyway if VMXON kicks in while PT
> is running.

Right, so I question the whole 'lets not schedule PT when VMX' premise,
it leads to inconsistencies all over. How about we treat it like
->add() succeeded and VMX simply results in no output.

Esp. when you then emit 'fake' data into/from a vmlaunch/vmresume
instruction.

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[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

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