Re: [PATCH 0/5] perf: add support for capturing skid IP

From	Stephane Eranian <eranian@google.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 0/5] perf: add support for capturing skid IP
Date	2017-06-16 19:10 +0200
Message-ID	<tT2UV-30W-7@gated-at.bofh.it> (permalink)
References	(6 earlier) <tSJyV-78N-3@gated-at.bofh.it> <tSLr4-8li-17@gated-at.bofh.it> <tSMdr-qd-9@gated-at.bofh.it> <tSToB-4Ym-5@gated-at.bofh.it> <tT1YS-2mF-9@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Fri, Jun 16, 2017 at 9:06 AM, Andi Kleen <ak@linux.intel.com> wrote:
> On Thu, Jun 15, 2017 at 11:52:07PM -0700, Stephane Eranian wrote:
>> Andi,
>>
>> On Thu, Jun 15, 2017 at 4:18 PM, Andi Kleen <ak@linux.intel.com> wrote:
>> >> Looking at this approach, the user interface is straightforward,
>> >> implementation in the x86 code is a bit more hairy because of the way
>> >> the branch_stack is captured, via the cpuc->lbr_entries. If you assume
>> >> that SKID_IP cannot be used with any other branch stack mode, then it
>> >> is easy. It becomes messy if you don't.
>> >
>> > That should be fine. After all if you have real LBRs you don't need
>> > the skid IP.
>> >
>> Yes, you still do. This is not the same thing. LBR captures only taken branches.
>> I care about taken AND non-taken branches and I don't want to sample on a
>> non-taken event, assuming it is available.
>
> Ok that's a reasonable argument for reporting it separately, like
> in your original patch.
>
Yeah, I think it is easier and more portable, especially on hardware with a
PEBS-like mechanism but no branch buffer (like LBR). FYI, I did do a test
implementation yesterday to evaluate the difficulty.

> -Andi

Thread

[PATCH 0/5] perf: add support for capturing skid IP Stephane Eranian <eranian@google.com> - 2017-06-15 16:00 +0200
  [PATCH 2/5] perf/x86: add PERF_SAMPLE_SKID_IP support for X86 PEBS Stephane Eranian <eranian@google.com> - 2017-06-15 16:00 +0200
    RE: [PATCH 2/5] perf/x86: add PERF_SAMPLE_SKID_IP support for X86  PEBS "Liang, Kan" <kan.liang@intel.com> - 2017-06-15 17:50 +0200
      Re: [PATCH 2/5] perf/x86: add PERF_SAMPLE_SKID_IP support for X86 PEBS Stephane Eranian <eranian@google.com> - 2017-06-15 18:40 +0200
        RE: [PATCH 2/5] perf/x86: add PERF_SAMPLE_SKID_IP support for X86  PEBS "Liang, Kan" <kan.liang@intel.com> - 2017-06-15 19:20 +0200
        Re: [PATCH 2/5] perf/x86: add PERF_SAMPLE_SKID_IP support for X86 PEBS Stephane Eranian <eranian@google.com> - 2017-06-15 21:20 +0200
  [PATCH 3/5] perf/tools: add support for PERF_SAMPLE_SKID_IP Stephane Eranian <eranian@google.com> - 2017-06-15 16:00 +0200
  [PATCH 4/5] perf/record: add support for sampling skid ip Stephane Eranian <eranian@google.com> - 2017-06-15 16:00 +0200
  Re: [PATCH 0/5] perf: add support for capturing skid IP Andi Kleen <ak@linux.intel.com> - 2017-06-15 17:20 +0200
    Re: [PATCH 0/5] perf: add support for capturing skid IP Stephane Eranian <eranian@google.com> - 2017-06-15 18:50 +0200
      Re: [PATCH 0/5] perf: add support for capturing skid IP Andi Kleen <ak@linux.intel.com> - 2017-06-15 19:30 +0200
        Re: [PATCH 0/5] perf: add support for capturing skid IP Stephane Eranian <eranian@google.com> - 2017-06-15 21:40 +0200
          Re: [PATCH 0/5] perf: add support for capturing skid IP Andi Kleen <ak@linux.intel.com> - 2017-06-15 22:10 +0200
            Re: [PATCH 0/5] perf: add support for capturing skid IP Stephane Eranian <eranian@google.com> - 2017-06-15 22:30 +0200
              Re: [PATCH 0/5] perf: add support for capturing skid IP Stephane Eranian <eranian@google.com> - 2017-06-16 00:30 +0200
                Re: [PATCH 0/5] perf: add support for capturing skid IP Andi Kleen <ak@linux.intel.com> - 2017-06-16 01:20 +0200
                Re: [PATCH 0/5] perf: add support for capturing skid IP Stephane Eranian <eranian@google.com> - 2017-06-16 09:00 +0200
                Re: [PATCH 0/5] perf: add support for capturing skid IP Andi Kleen <ak@linux.intel.com> - 2017-06-16 18:10 +0200
                Re: [PATCH 0/5] perf: add support for capturing skid IP Stephane Eranian <eranian@google.com> - 2017-06-16 19:10 +0200
                Re: [PATCH 0/5] perf: add support for capturing skid IP Stephane Eranian <eranian@google.com> - 2017-06-16 19:20 +0200
                Re: [PATCH 0/5] perf: add support for capturing skid IP Andi Kleen <ak@linux.intel.com> - 2017-06-16 20:00 +0200
                Re: [PATCH 0/5] perf: add support for capturing skid IP Stephane Eranian <eranian@google.com> - 2017-06-16 21:20 +0200

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