Hi Deepthi,

Texas Instruments France SA, 821 Avenue Jack Kilby, 06270 Villeneuve Loubet. 036 420 040 R.C.S Antibes. Capital de EUR 753.920

-----Original Message-----

From: Deepthi Dharwar [mailto:deepthi at linux.vnet.ibm.com]
Sent: Wednesday, November 09, 2011 12:13 PM
To: Hilman, Kevin
Cc: linux-kernel at vger.kernel.org; Arjan van de Ven; linux-arm-
kernel at lists.infradead.org; linux-omap at vger.kernel.org; linux-
pm at lists.linux-foundation.org; Chalhoub, Nicole
Subject: Re: [PATCH] CPUIdle: Reevaluate C-states under CPU load to favor
deeper C-states

[...]

By setting timers when we enter non-deepest C-state possible, such that
when it fires we
can re-evaluate and try moving into deeper and deeper C-states enhancing
the
power savings is a good feature to have.

Looking at the current implementation, is it possible to have it as
configurable option
where one can enable/disable this functionality through the backhand
driver ?

The timeout values of the c state timers are set in the backhand driver.
By setting the timeout to 0 the timers will not fire so you'll not have this functionality enabled

Also I am thinking, instead of having them in governor
wouldnt it be a good idea to have it implemented in
the backhand driver itself ?
--Deepthi

In fact each C-state had its own configurable timer, so it is a parameter characterizing a C-state as it is for the exit_latency and target_residency parameters.
And we wanted the timer to fire only when we do not go in deep Cstate due to a high load. This decision is made in the CPU idle governor. So the functionality should be seen from the governor..

Thanks and Regards
Nicole