linux-kernel - Re: [PATCH] tracing, perf: add more power related events

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Message-ID: <AANLkTikmcMZhJh348vcVkPwWRyXot8m+==484tY=cEkD@mail.gmail.com>
Date:	Wed, 29 Sep 2010 11:25:43 +0200
From:	Jean Pihet <jean.pihet@...oldbits.com>
To:	Thomas Renninger <trenn@...e.de>
Cc:	Arjan van de Ven <arjan@...ux.intel.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	Len Brown <len.brown@...el.com>, arjan@...radead.org,
	Kevin Hilman <khilman@...prootsystems.com>,
	linux-kernel@...r.kernel.org, linux-pm@...ts.linux-foundation.org,
	linux-omap@...r.kernel.org, linux-perf-users@...r.kernel.org,
	linux-trace-users@...r.kernel.org
Subject: Re: [PATCH] tracing, perf: add more power related events

Hi,

On Wed, Sep 29, 2010 at 9:49 AM, Thomas Renninger <trenn@...e.de> wrote:
> On Tuesday 28 September 2010 23:45:24 Arjan van de Ven wrote:
>>   On 9/28/2010 2:22 PM, Rafael J. Wysocki wrote:
>> > On Tuesday, September 28, 2010, Jean Pihet wrote:
>> >> Hi,
>> > Hi,
>> >
>> >> Here is what I am proposing, in reply to all your comments:
>> >>
>> >> 1) rename the events to match Thomas's proposal:
>> >>     power:power_cpu_cstate
>> >>     power:power_cpu_pstate
>> >>     power:power_cpu_sstate
> I'd not name it that X86/ACPI specific.
>    power:processor_sleep
>    power:processor_frequency
>    power:system_suspend
> This would map with X86/ACPI c/p/s states but the name would
> also match fine with ARM and other archs.
Good for me!

>
>> > If that sstate thing is going to mean "suspend", then please drop
>> > it.
>> > "Suspend" is not a state, let alone a CPU state.  It is a procedure
>> > by which the (entire) system is put into a sleep state (that is not
>> > confined to CPUs).
>>
>> there are also non-suspend S states, like S0i1 and S0i3 (supported in
>> the current Intel "Moorestown" platform)
>>
>> so it's slightly more complex than "just" suspend :)
> Something specific for this arch could get introduced, similar as
> Jean did for the ARM specifics, e.g.:
> power:moorestown_suspend
I would not introduce arch specific events. Your other proposal below
is more generic.

> Intel probably invented three names for this new technique, one
> might fit as an event name?
> Depending whether extra info needs passed through this event it
> could also use
>    power:system_suspend
> and pass a suspend state of #define S0i1 0x100, #define S0i2 0x101...
I am OK with that.

>
> I try to find time to come up with another cleanup patch.
> I also want to look at perf timechart then where I remember some ugly
> hacks with C-state accounting and the broken state_start, state_end and
> frequency_switch events. Hope it won't get too ugly and perf timechart
> can support both, the old and the cleaned up events for a while.
About pytimechart, I think it should be updated with the support for
the new events only. The current version is not perfect but supports
the current events correctly. I am planning to celan up and upgrade
that tool when the new API is out.

If that could force people to upgrade to the new events API asap...

>
>    Thomas
>
I know you want to see real code. Let me come with a respin of the
patch asap (it is a matter of days).

Thanks,
Jean
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