linux-kernel - Re: Invalid event (cycles:pp) in per-thread mode, enable system wide with '-a'.

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Date:   Fri, 30 Sep 2022 10:01:59 +0530
From:   Ravi Bangoria <ravi.bangoria@....com>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     Slade Watkins <srw@...dewatkins.net>,
        linux-perf-users <linux-perf-users@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ian Rogers <irogers@...gle.com>,
        Namhyung Kim <namhyung@...il.com>,
        Ravi Bangoria <ravi.bangoria@....com>
Subject: Re: Invalid event (cycles:pp) in per-thread mode, enable system wide
 with '-a'.

On 30-Sep-22 9:56 AM, Namhyung Kim wrote:
> Hello,
> 
> On Thu, Sep 29, 2022 at 8:49 PM Ian Rogers <irogers@...gle.com> wrote:
>>
>> On Thu, Sep 29, 2022 at 3:10 PM Slade Watkins <srw@...dewatkins.net> wrote:
>>>
>>> Hey Nick,
>>>
>>>> On Sep 29, 2022, at 5:54 PM, Nick Desaulniers <ndesaulniers@...gle.com> wrote:
>>>>
>>>> I remember hearing rumblings about issues with zen 2, LBR, vs zen 3.
>>>> Is this a known issue, or am I holding it wrong?
>>>
>>> Hm… I also remember this. I have a Zen 2 based system that I can do testing on, so I will do so when I’m able.
>>>
>>> If I discover something of note, I’ll get back to you.
>>>
>>> Cheers,
>>> -srw
>>>
>>
>> LBR isn't yet supported for Zen but is coming:
>> https://lore.kernel.org/lkml/166155216401.401.5809694678609694438.tip-bot2@tip-bot2/
>> I'd recommend frame-pointers.
>>
>> +Ravi who may be able to say if there are any issues with the precise
>> sampling on AMD.
> 
> Afaik cvcles:pp will use IBS but it doesn't support per-task profiling
> since it has no task context.  Ravi is working on it..

Right.
https://lore.kernel.org/lkml/20220829113347.295-1-ravi.bangoria@amd.com

Thanks,
Ravi