linux-kernel - RE: [PATCH V2 1/1] perf/x86: Add Intel power cstate PMUs support

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Message-ID: <37D7C6CF3E00A74B8858931C1DB2F077018D33A7@SHSMSX103.ccr.corp.intel.com>
Date:	Thu, 6 Aug 2015 20:25:45 +0000
From:	"Liang, Kan" <kan.liang@...el.com>
To:	Stephane Eranian <eranian@...gle.com>
CC:	Peter Zijlstra <peterz@...radead.org>,
	"mingo@...hat.com" <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH V2 1/1] perf/x86: Add Intel power cstate PMUs support


> >> >> >> +static cpumask_t power_cstate_core_cpu_mask;
> >> >> >
> >> >> > That one typically does not need a cpumask.
> >> >> >
> >> >> You need to pick one CPU out of the multi-core. But it is for
> >> >> client parts thus there is only one socket. At least this is my
> understanding.
> >> >>
> >> >
> >> > CORE_C*_RESIDENCY are available for physical processor core.
> >> > So logical processor in same physical processor core share the same
> >> > counter.
> >> > I think we need the cpumask to identify the default logical
> >> > processor which do counting.
> >> >
> >> Did you restrict these events to system-wide mode only?
> >>
> Ok, so that means that your cpumask includes one HT per physical core.
> But then, the result is not the simple aggregation of all the N/2 CPUs.

The counter counts per physical core. The result is the aggregation of
all HT cpus in same physical core.
It's similar as per socket counter. But the scope is physical core now.