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

["Rafael J. Wysocki" <rjw@sisk.pl>]

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

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).

>    ...
> 
> 2) introduce a new Kconfig option CONFIG_DEPRECATED_POWER_EVENTS and
> conditionally map a subset of the new events to the old ones for
> backward compatibility with the existing user apps. The apps should be
> converted to the new API asap,
> 
> 3) update documentation

Sounds reasonable.

> Other remarks here below:
> 
> On Wed, Sep 22, 2010 at 8:49 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> ...
> > This POWER_SSTATE thing seems to be totally artificial and omap-specific.
> >
> > Why do you want it to be done this way?
> >
> > Or is the ACPI handling added in the ACPI patch?  In which case, why don't you
> > put that power_switch_state(POWER_SSTATE, 1, 0, cpu) into
> > kernel/power/suspend.c:suspend_enter() (and analogously for
> > power_switch_state(POWER_SSTATE, 0, 0, cpu)).
> The ACPI code is not using the SSTATE event.
> Indeed inserting a tracepoint at
> kernel/power/suspend.c:suspend_enter() is more generic. I will correct
> this.

OK

> > Moreover, why is the cpu argument necessary for POWER_SSTATE at all?
> The cpu_id parameter is present in all events prototypes. This is not
> needed. I will correct this.

OK

Thanks,
Rafael