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Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during per-process profiling of STREAM benchmark on Intel Xeon Phi

From Mark Rutland <mark.rutland@arm.com>
Newsgroups linux.kernel
Subject Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during per-process profiling of STREAM benchmark on Intel Xeon Phi
Date 2017-06-19 18:00 +0200
Message-ID <tU7fR-4Bo-35@gated-at.bofh.it> (permalink)
References (5 earlier) <tU6jM-3YD-27@gated-at.bofh.it> <tU6D8-4lE-15@gated-at.bofh.it> <tU6MO-4pB-23@gated-at.bofh.it> <tU6MQ-4pB-63@gated-at.bofh.it> <tU76c-4xl-91@gated-at.bofh.it>
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On Mon, Jun 19, 2017 at 08:39:18AM -0700, Andi Kleen wrote:
> On Mon, Jun 19, 2017 at 04:24:01PM +0100, Mark Rutland wrote:
> > On Mon, Jun 19, 2017 at 08:21:51AM -0700, Andi Kleen wrote:
> > > > I was trying to get a feel for how that compares to what we can do
> > > > today. For other reasons (e.g. fd exhaustion), opening NR_CPUS * n
> > > 
> > > You just have to increase the fd limit. The 1024 fd default is just
> > > archaic for larger systems and doesn't really make any sense because
> > > it only controls very small amounts of kernel memory.
> > > 
> > > > events might not be a great idea on systems with a huge number of CPUs.
> > > > We might want a heuristic in the perf tool regardless.
> > > 
> > > But there's no alternative: we have to measure all CPUs with all events.
> > 
> > You can measure the process on all CPUs by using 1 event without a CPU
> > filter, rather than NR_CPUS events.
> 
> That wouldn't measure all threads, at least not with current perf core.

Ah; I missed the constraint imposed by perf_mmap().

For some reason I thought that was enforced by userspace only.

Sorry for the noise.

Mark.

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[PATCH v3 1/n] perf/core: addressing 4x slowdown during per-process  profiling of STREAM benchmark on Intel Xeon Phi Alexey Budankov <alexey.budankov@linux.intel.com> - 2017-06-15 19:50 +0200
  Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Mark Rutland <mark.rutland@arm.com> - 2017-06-15 22:00 +0200
    Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Alexey Budankov <alexey.budankov@linux.intel.com> - 2017-06-16 00:20 +0200
      Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Mark Rutland <mark.rutland@arm.com> - 2017-06-16 11:20 +0200
        Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Alexey Budankov <alexey.budankov@linux.intel.com> - 2017-06-16 16:10 +0200
          Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Alexey Budankov <alexey.budankov@linux.intel.com> - 2017-06-16 16:30 +0200
            Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Mark Rutland <mark.rutland@arm.com> - 2017-06-19 14:50 +0200
              Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Mark Rutland <mark.rutland@arm.com> - 2017-06-19 15:40 +0200
                Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Alexey Budankov <alexey.budankov@linux.intel.com> - 2017-06-19 16:10 +0200
                Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Andi Kleen <ak@linux.intel.com> - 2017-06-19 17:00 +0200
                Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Mark Rutland <mark.rutland@arm.com> - 2017-06-19 17:20 +0200
                Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Andi Kleen <ak@linux.intel.com> - 2017-06-19 17:30 +0200
                Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Mark Rutland <mark.rutland@arm.com> - 2017-06-19 17:30 +0200
                Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Andi Kleen <ak@linux.intel.com> - 2017-06-19 17:50 +0200
                Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Mark Rutland <mark.rutland@arm.com> - 2017-06-19 18:00 +0200
      Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Alexey Budankov <alexey.budankov@linux.intel.com> - 2017-06-19 15:10 +0200
        Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Mark Rutland <mark.rutland@arm.com> - 2017-06-19 15:30 +0200
          Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Alexey Budankov <alexey.budankov@linux.intel.com> - 2017-06-19 15:40 +0200
            Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Alexey Budankov <alexey.budankov@linux.intel.com> - 2017-06-19 17:10 +0200
              Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Andi Kleen <ak@linux.intel.com> - 2017-06-19 17:30 +0200
                Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Alexey Budankov <alexey.budankov@linux.intel.com> - 2017-06-19 17:40 +0200
            Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Mark Rutland <mark.rutland@arm.com> - 2017-06-19 17:20 +0200
              Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Alexey Budankov <alexey.budankov@linux.intel.com> - 2017-06-19 17:30 +0200
    Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during  per-process profiling of STREAM benchmark on Intel Xeon Phi Alexey Budankov <alexey.budankov@linux.intel.com> - 2017-06-19 22:40 +0200

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