Re: [RFC PATCH 1/6] perf: Move mlock accounting to ring buffer allocation

From	Alexander Shishkin <alexander.shishkin@linux.intel.com>
Newsgroups	linux.kernel
Subject	Re: [RFC PATCH 1/6] perf: Move mlock accounting to ring buffer allocation
Date	2016-09-23 18:00 +0200
Message-ID	<skB3j-5Jn-3@gated-at.bofh.it> (permalink)
References	<skwQ1-2Yn-11@gated-at.bofh.it> <skwQ2-2Yn-29@gated-at.bofh.it> <skxCq-3yR-33@gated-at.bofh.it> <skzNT-4QO-23@gated-at.bofh.it> <skAAi-5zK-21@gated-at.bofh.it>
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Peter Zijlstra <peterz@infradead.org> writes:

> On Fri, Sep 23, 2016 at 05:27:22PM +0300, Alexander Shishkin wrote:
>> > Afaict there's no actual need to hide the AUX buffer for this sampling
>> > stuff; the user knows about all this and can simply mmap() the AUX part.
>> 
>> Yes, you're right here. We could also re-use the AUX record, adding a
>> new flag for this. It may be even better if I can work out the
>> inheritance (the current code doesn't handle inheritance at the moment
>> in case we decide to scrap it).
>
> What is the exact problem with inheritance? You can inherit PT (and
> other) events just fine, and their output redirects to the original
> (AUX) buffer too.
>
> Is the problem untangling which part of the AUX buffer belongs to which
> task upon sample?

Tasks we can figure out from id samples on RECORD_AUX (assuming we're
using those), but which event (if you have multiple) does a sample
belong to is trickier.

Cutting out samples becomes more interesting as normally RECORD_AUX
don't overlap, we can keep it that way and then the samples will
naturally be non-overlapping, but will all be different sizes. And there
is a question of waking up the consumer often enough to copy out all the
samples before the buffer overwrites itself. Let me think a bit.

Regards,
--
Alex

Thread

[RFC PATCH 0/6] perf: Add AUX data sampling Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-09-23 13:30 +0200
  [RFC PATCH 1/6] perf: Move mlock accounting to ring buffer allocation Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-09-23 13:30 +0200
    Re: [RFC PATCH 1/6] perf: Move mlock accounting to ring buffer  allocation Peter Zijlstra <peterz@infradead.org> - 2016-09-23 14:20 +0200
      Re: [RFC PATCH 1/6] perf: Move mlock accounting to ring buffer allocation Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-09-23 16:40 +0200
        Re: [RFC PATCH 1/6] perf: Move mlock accounting to ring buffer  allocation Peter Zijlstra <peterz@infradead.org> - 2016-09-23 17:30 +0200
          Re: [RFC PATCH 1/6] perf: Move mlock accounting to ring buffer allocation Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-09-23 18:00 +0200
      Re: [RFC PATCH 1/6] perf: Move mlock accounting to ring buffer  allocation Andi Kleen <ak@linux.intel.com> - 2016-09-23 19:30 +0200
        Re: [RFC PATCH 1/6] perf: Move mlock accounting to ring buffer  allocation Peter Zijlstra <peterz@infradead.org> - 2016-09-23 22:30 +0200
          Re: [RFC PATCH 1/6] perf: Move mlock accounting to ring buffer allocation Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-09-26 10:30 +0200
            Re: [RFC PATCH 1/6] perf: Move mlock accounting to ring buffer  allocation Peter Zijlstra <peterz@infradead.org> - 2016-09-26 11:10 +0200
              Re: [RFC PATCH 1/6] perf: Move mlock accounting to ring buffer allocation Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-09-26 14:50 +0200
              Re: [RFC PATCH 1/6] perf: Move mlock accounting to ring buffer allocation Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-09-26 18:20 +0200
  [RFC PATCH 2/6] perf: Add api to (de-)allocate AUX buffers for kernel counters Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-09-23 13:40 +0200
  [RFC PATCH 3/6] perf: Add a helper for looking up pmus by type Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-09-23 13:40 +0200
  [RFC PATCH 4/6] perf: Add infrastructure for using AUX data in perf samples Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-09-23 13:40 +0200
  [RFC PATCH 5/6] perf: Disable PMU around address filter adjustment Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-09-23 13:40 +0200
  [RFC PATCH 6/6] perf: Disable IRQs in address filter sync path Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-09-23 13:40 +0200
    Re: [RFC PATCH 6/6] perf: Disable IRQs in address filter sync path Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2016-09-26 18:30 +0200
      Re: [RFC PATCH 6/6] perf: Disable IRQs in address filter sync path Mathieu Poirier <mathieu.poirier@linaro.org> - 2016-10-04 18:50 +0200
  Re: [RFC PATCH 0/6] perf: Add AUX data sampling Peter Zijlstra <peterz@infradead.org> - 2016-09-23 13:50 +0200
    Re: [RFC PATCH 0/6] perf: Add AUX data sampling Andi Kleen <ak@linux.intel.com> - 2016-09-23 19:20 +0200
      Re: [RFC PATCH 0/6] perf: Add AUX data sampling Peter Zijlstra <peterz@infradead.org> - 2016-09-23 22:40 +0200
        Re: [RFC PATCH 0/6] perf: Add AUX data sampling Andi Kleen <ak@linux.intel.com> - 2016-09-24 00:40 +0200

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