Messages in this thread | | | Date | Tue, 18 Mar 2014 12:25:14 -0700 | From | Dirk Brandewie <> | Subject | Re: [PATCH v3 0/2] Add stop callback to the cpufreq_driver interface. |
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On 03/18/2014 12:08 PM, Srivatsa S. Bhat wrote: > On 03/18/2014 10:52 PM, dirk.brandewie@gmail.com wrote: >> From: Dirk Brandewie <dirk.j.brandewie@intel.com> >> > > I don't mean to nitpick, but generally its easier to deal with > patchsets if you post the subsequent versions in fresh email threads. > Otherwise it can get a bit muddled along with too many other email > discussions in the same thread :-( > >> Changes: >> v2->v3 >> Changed the calling of the ->stop() callback to be conditional on the >> core being the last core controlled by a given policy. >> > > Wait, why? I'm sorry if I am not catching up with the discussions on > this issue quickly enough, but I don't see why we should make it > conditional on _that_. I thought we agreed that we should make it > conditional in the sense that ->stop() should be invoked only for > ->setpolicy drivers, right?
This was done at Viresh's suggestion since thought there might be value for ->target drivers.
Any of the options work for me called only for set_policy scaling drivers called unconditionally for all scaling drivers called for last core controlled by a given policy
> > The way I look at it, ->stop() gives you a chance to stop managing > the CPU going offline. As in "stop this CPU". ->exit() is your chance > to cleanup the policy, since all its users have gone offline (or this > is the last CPU belonging to that policy which is going offline). > > With this in mind, we should invoke ->stop() every time we take a > CPU offline, and invoke ->exit() only when the last CPU in the policy > goes offline.
This is exactly what will happen for intel_pstate since the policies cover a single core.
I will defer to you and Viresh how policies that affect more that one cpu should be handled.
What intel_pstate needs it to be called during the PREPARE phase of the offline process.
> > What am I missing? > > Regards, > Srivatsa S. Bhat >
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