linux-kernel - Re: [PATCH v2] perf stat: enable 1ms interval for printing event counters values

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Date:   Wed, 4 Apr 2018 10:39:20 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Alexey Budankov <alexey.budankov@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] perf stat: enable 1ms interval for printing event
 counters values

Em Wed, Apr 04, 2018 at 09:05:16AM +0200, Jiri Olsa escreveu:
> On Tue, Apr 03, 2018 at 09:18:33PM +0300, Alexey Budankov wrote:
> > 
> > Currently print count interval for performance counters values is 
> > limited by 10ms so reading the values at frequencies higher than 100Hz 
> > is restricted by the tool.
> > 
> > This change makes perf stat -I possible on frequencies up to 1KHz and, 
> > to some extent, makes perf stat -I to be on-par with perf record 
> > sampling profiling.
> > 
> > When running perf stat -I for monitoring e.g. PCIe uncore counters and 
> > at the same time profiling some I/O workload by perf record e.g. for 
> > cpu-cycles and context switches, it is then possible to observe 
> > consolidated CPU/OS/IO(Uncore) performance picture for that workload.
> > 
> > Tool overhead warning printed when specifying -v option can be missed 
> > due to screen scrolling in case you have output to the console 
> > so message is moved into help available by running perf stat -h.
> > 
> > Signed-off-by: Alexey Budankov <alexey.budankov@...ux.intel.com>
> > ---
> > 
> > Changes in v2:
> >  - updated minimum value to 1ms at perf-stat.txt manual
> 
> Acked-by: Jiri Olsa <jolsa@...nel.org>

Thanks, applied to perf/core.

- Arnaldo