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

[Stephane Eranian]

On Mon, Feb 5, 2018 at 7:17 AM, Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> On Fri, Feb 02, 2018 at 01:04:34PM -0800, Stephane Eranian wrote:
>> On Fri, Feb 2, 2018 at 12:40 PM, Arnaldo Carvalho de Melo
>> <acme@xxxxxxxxxx> wrote:
>> > Em Fri, Feb 02, 2018 at 05:28:49PM -0300, Arnaldo Carvalho de Melo escreveu:
>> >> Em Fri, Feb 02, 2018 at 10:45:46AM -0800, Stephane Eranian escreveu:
>> >> > Otherwise, I tested what you have written so far and it works.
>> >
>> >> So I take that as a Tested-by: Stephane and will apply the patches, Jiri
>> >> can continue working on these other aspects, right?
>> >
>> > I also added this for the casual reader to get up to speed more quickly,
>> > please check that it makes sense.
>> >
>> >     Committer note:
>> >
>> >     When we use -c or a period=N term in the event definition, then we don't
>> >     need to ask the kernel, via perf_event_attr.sample_type |=
>> >     PERF_SAMPLE_PERIOD, to put the event period in each sample, as we know
>> >     it already, it is in perf_event_attr.sample_period.
>> >
>> Not quite. It depends on how each event is setup. I can mix & match period
>> and frequency. The PERF_SAMPLE_PERIOD can be dropped only if all the
>> events use a fixed period either via period=N or -c.
>
> I think you can have both period and freq based event in one session
> if that's your concern..? what would be the problem?
>
My understanding was that perf only support configs where all events
have the same attr.sample_type. With frequency mode, you'd want the period
recorded in some cases.

> jirka
>
>> I hope that perf report can deal with config mixing period and fixed
>> mode correctly.