2022-09-29 22:30:41

by Slade Watkins

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

Hey Nick,

> On Sep 29, 2022, at 5:54 PM, Nick Desaulniers <[email protected]> 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

2022-09-30 04:13:14

by Ian Rogers

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

On Thu, Sep 29, 2022 at 3:10 PM Slade Watkins <[email protected]> wrote:
>
> Hey Nick,
>
> > On Sep 29, 2022, at 5:54 PM, Nick Desaulniers <[email protected]> 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.

Thanks,
Ian

2022-09-30 05:15:48

by Namhyung Kim

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

Hello,

On Thu, Sep 29, 2022 at 8:49 PM Ian Rogers <[email protected]> wrote:
>
> On Thu, Sep 29, 2022 at 3:10 PM Slade Watkins <[email protected]> wrote:
> >
> > Hey Nick,
> >
> > > On Sep 29, 2022, at 5:54 PM, Nick Desaulniers <[email protected]> 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..

Thanks,
Namhyung