linux-kernel - Re: [PATCH 0/5] Support metric group constraint

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Message-ID: <20200220164317.GG160988@tassilo.jf.intel.com>
Date:   Thu, 20 Feb 2020 08:43:17 -0800
From:   Andi Kleen <ak@...ux.intel.com>
To:     "Liang, Kan" <kan.liang@...ux.intel.com>
Cc:     Jiri Olsa <jolsa@...hat.com>, acme@...nel.org, mingo@...hat.com,
        peterz@...radead.org, linux-kernel@...r.kernel.org,
        mark.rutland@....com, namhyung@...nel.org,
        ravi.bangoria@...ux.ibm.com, yao.jin@...ux.intel.com
Subject: Re: [PATCH 0/5] Support metric group constraint

> For other metric groups, even they have cycles, the issue should not be
> triggered.
> For example, if they have 4 or less events, the cycles can be scheduled to
> GP counter instead.
> If they have 6 or more events, the weak group will be reject anyway.
> Perf tool will open it as non-group (standalone metrics).

Technically it can also happen for 9 events with Hyper Threading off or
on Icelake (8 generic counters)

I didn't think we had any of those, but please double check.

-Andi