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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CABPqkBSQS6mMkY-uC0-qE0vLVs0CUGP--iFvFci4z0_BzZWyOw@mail.gmail.com>
Date:	Thu, 6 Aug 2015 13:38:21 -0700
From:	Stephane Eranian <eranian@...gle.com>
To:	"Liang, Kan" <kan.liang@...el.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

On Thu, Aug 6, 2015 at 1:25 PM, Liang, Kan <kan.liang@...el.com> wrote:
>
>> >> >> >> +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.

But then don't you need to divide by 2 to get a meaningful result?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/