Re: [PATCH V7 07/14] perf/core: Add a new PERF_EV_CAP_COEXIST event capability

[Peter Zijlstra]

On Fri, Jul 24, 2020 at 10:19:25AM -0400, Liang, Kan wrote:
> There will be a problem for the current perf tool, which assumes that the
> leader event is the sampling event.
> 
> I will check how can we specially handle it in the perf tool.

Ah, okay. I've long lost track of how the tool works :/

Something that seems to 'work' is:
'{cycles,cpu/instructions,period=50000/}', so maybe you can make the
group modifier :S use any sampling event if there is one, and otherwise
designate the leader.

Then you can write things like:

  '{slots, metric1, metric2, cpu/cycles,freq=50000/}:S'

and then since cycles is specified as a sampling event, it will use
that.