linux-kernel - Re: [PATCH 1/3] perf tools: Fix period/freq terms setup

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Date:   Sat, 3 Feb 2018 16:19:20 -0800
From:   Stephane Eranian <eranian@...gle.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Jiri Olsa <jolsa@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        David Ahern <dsahern@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH 1/3] perf tools: Fix period/freq terms setup

On Sat, Feb 3, 2018 at 7:30 AM, Jiri Olsa <jolsa@...hat.com> wrote:
> On Fri, Feb 02, 2018 at 10:45:46AM -0800, Stephane Eranian wrote:
>> Jiri,
>>
>> On Thu, Feb 1, 2018 at 12:38 AM, Jiri Olsa <jolsa@...nel.org> wrote:
>> > Stephane reported that we don't set properly PERIOD
>> > sample type for events with period term defined.
>> >
>> > Before:
>> >   $ perf record -e cpu/cpu-cycles,period=1000/u ls
>> >   $ perf evlist -v
>> >   cpu/cpu-cycles,period=1000/u: ... sample_type: IP|TID|TIME|PERIOD, ...
>> >
>> > After:
>> >   $ perf record -e cpu/cpu-cycles,period=1000/u ls
>> >   $ perf evlist -v
>> >   cpu/cpu-cycles,period=1000/u: ... sample_type: IP|TID|TIME, ...
>> >
>> > Setting PERIOD sample type based on period term setup.
>> >
>> there is still one problem remaining here. It has to do with the handling
>> of cycles:pp or :p or :ppp. Suppose I want to set a period for it while I am
>> also sampling on other events: Something like:
>>
>> $ perf record -e
>> cycles:pp,instructions,cpu/event=0xd0,umaks=0x81,period=100000/ .....
>>
>> I want to set the period for cycles:pp, but not for instructions. I
>> cannot use -c because
>> it would also force a period on instructions. I could use the raw hw
>> raw event code for cycles:pp.
>> But that does not work because recent kernels prevent use of hw
>> filters on events programmed
>> for PEBS, e.g., cpu/event=0xc2,umask=0x1,cmask=16,inv/pp is rejected.
>> PEBS does not support filters.
>> It works in the case of cycles:pp simply by the nature on the
>> underlying event and the stalls.
>>
>> To get precise cycles, the only event syntax you can use is cycles:pp,
>> but then you cannot specify
>> an event-specific period. This needs to be fixed as well.
>
> you can use p modifier behind like: cpu/.../pp
>
>>
>> I'd like to be able to say:
>>
>> $ perf record -e
>> cycles:pp:period=10000001,cpu/event=0xd0,umaks=0x81,period=100000/
>>
>> Or something equivalent.
>
> and you can specify terms for hw events like 'cycles'
>
> [jolsa@...va perf]$ sudo ./perf record -e 'cycles/period=10000001/pp,cpu/event=0xd0,umask=0x81,period=100000/'
> ^C[ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 0.579 MB perf.data (722 samples) ]
>
Ok, I did not know about this syntax. It looks bizarre because you are
using an event name as a PMU instance.
Works for me.
Thanks.

> [jolsa@...va perf]$ ./perf evlist -v
> cycles/period=10000001/pp: size: 112, { sample_period, sample_freq }: 10000001, sample_type: IP|TID|TIME|ID|CPU, read_format: ID, disabled: 1, inherit: 1, mmap: 1, comm: 1, task: 1, precise_ip: 2, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1
> cpu/event=0xd0,umask=0x81,period=100000/: type: 4, size: 112, config: 0x81d0, { sample_period, sample_freq }: 100000, sample_type: IP|TID|TIME|ID|CPU, read_format: ID, disabled: 1, inherit: 1, sample_id_all: 1, exclude_guest: 1
>
> jirka