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Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter

From Andi Kleen <ak@linux.intel.com>
Newsgroups linux.kernel
Subject Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter
Date 2017-05-24 19:00 +0200
Message-ID <tKHNE-4Oc-7@gated-at.bofh.it> (permalink)
References (4 earlier) <tK1bI-1hH-7@gated-at.bofh.it> <tKbE5-7Qs-9@gated-at.bofh.it> <tKbNL-7U4-1@gated-at.bofh.it> <tKGHT-49Y-9@gated-at.bofh.it> <tKH1f-4vB-5@gated-at.bofh.it>
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> The whole point of the rdpmc() implementation is to be low overhead.
> If you have to parse 10 different mmap() fields it starts to defeat the 
> purpose.

You would only use it with ref-cycles of course. So for the normal
case there is no overhead.

> If the watchdog counter is constantly running, can't you just modify 
> perf_event to just grab start/stop values at context switch time and 
> provide the difference to the user?  Sort of like the "always running" 
> patchsets that float around? Though I guess that doesn't help much with 
> sampling.

This wouldn't work with ring filters unfortunately. 

-Andi

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[PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter kan.liang@intel.com - 2017-05-19 20:00 +0200
  [PATCH 2/2] perf/x86/intel, watchdog: Switch NMI watchdog to ref cycles on x86 kan.liang@intel.com - 2017-05-19 20:00 +0200
    Re: [PATCH 2/2] perf/x86/intel, watchdog: Switch NMI watchdog to ref  cycles on x86 Peter Zijlstra <peterz@infradead.org> - 2017-05-22 14:10 +0200
      Re: [PATCH 2/2] perf/x86/intel, watchdog: Switch NMI watchdog to ref  cycles on x86 Peter Zijlstra <peterz@infradead.org> - 2017-05-22 14:10 +0200
      RE: [PATCH 2/2] perf/x86/intel, watchdog: Switch NMI watchdog to  ref cycles on x86 "Liang, Kan" <kan.liang@intel.com> - 2017-05-22 19:00 +0200
        Re: [PATCH 2/2] perf/x86/intel, watchdog: Switch NMI watchdog to ref  cycles on x86 Peter Zijlstra <peterz@infradead.org> - 2017-05-22 21:30 +0200
    Re: [PATCH 2/2] perf/x86/intel, watchdog: Switch NMI watchdog to ref  cycles on x86 Stephane Eranian <eranian@google.com> - 2017-05-22 20:30 +0200
      Re: [PATCH 2/2] perf/x86/intel, watchdog: Switch NMI watchdog to ref  cycles on x86 Andi Kleen <ak@linux.intel.com> - 2017-05-22 22:10 +0200
  Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Peter Zijlstra <peterz@infradead.org> - 2017-05-22 10:40 +0200
    Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Stephane Eranian <eranian@google.com> - 2017-05-22 20:20 +0200
  Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Peter Zijlstra <peterz@infradead.org> - 2017-05-22 11:30 +0200
    Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Peter Zijlstra <peterz@infradead.org> - 2017-05-22 14:30 +0200
      RE: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter "Liang, Kan" <kan.liang@intel.com> - 2017-05-22 19:00 +0200
    RE: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter "Liang, Kan" <kan.liang@intel.com> - 2017-05-22 19:00 +0200
      Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Peter Zijlstra <peterz@infradead.org> - 2017-05-22 21:30 +0200
        Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Stephane Eranian <eranian@google.com> - 2017-05-22 21:30 +0200
          RE: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter "Liang, Kan" <kan.liang@intel.com> - 2017-05-23 00:00 +0200
          Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Peter Zijlstra <peterz@infradead.org> - 2017-05-23 08:40 +0200
            Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Stephane Eranian <eranian@google.com> - 2017-05-23 08:50 +0200
              Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Andi Kleen <ak@linux.intel.com> - 2017-05-24 17:50 +0200
                Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP  counter Vince Weaver <vincent.weaver@maine.edu> - 2017-05-24 18:10 +0200
                Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Andi Kleen <ak@linux.intel.com> - 2017-05-24 19:00 +0200
                Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Stephane Eranian <eranian@google.com> - 2017-05-28 22:40 +0200
                Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Peter Zijlstra <peterz@infradead.org> - 2017-05-30 11:30 +0200
                Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Andi Kleen <ak@linux.intel.com> - 2017-05-30 16:00 +0200
                Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Peter Zijlstra <peterz@infradead.org> - 2017-05-30 18:30 +0200
                Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Stephane Eranian <eranian@google.com> - 2017-05-30 18:50 +0200
                Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Andi Kleen <ak@linux.intel.com> - 2017-05-30 19:30 +0200
                Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Peter Zijlstra <peterz@infradead.org> - 2017-05-30 19:50 +0200
                Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Andi Kleen <ak@linux.intel.com> - 2017-05-30 20:00 +0200
                Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Peter Zijlstra <peterz@infradead.org> - 2017-05-30 21:10 +0200
                Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Andi Kleen <ak@linux.intel.com> - 2017-05-30 21:50 +0200
                Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Stephane Eranian <eranian@google.com> - 2017-05-30 18:50 +0200
                Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP  counter Thomas Gleixner <tglx@linutronix.de> - 2017-05-30 19:00 +0200
                Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter Peter Zijlstra <peterz@infradead.org> - 2017-05-30 19:30 +0200
                Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP  counter Vince Weaver <vincent.weaver@maine.edu> - 2017-05-31 23:00 +0200
  Re: [PATCH 1/2] perf/x86/intel: enable CPU ref_cycles for GP counter kbuild test robot <lkp@intel.com> - 2017-05-28 05:00 +0200

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