From mboxrd@z Thu Jan 1 00:00:00 1970 From: Antti P Miettinen Subject: Re: [linux-pm] [PATCH 0/2] RFC: CPU frequency max as PM QoS param Date: Tue, 28 Feb 2012 11:37:55 +0200 Message-ID: <87ty2b5mdo.fsf@amiettinen-lnx.nvidia.com> References: <87d39fk2n3.fsf@ti.com> <20120217030453.GA3266@gs62> <87pqd94yeu.fsf@amiettinen-lnx.nvidia.com> <20120221145632.GA2840@envy17> <87linw5aod.fsf@ti.com> <20120225174449.GA17141@envy17> <877gz8wcud.fsf@ti.com> <4F4B9B60.6040501@nvidia.com> <20120228005630.GA15348@envy17> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: In-Reply-To: <20120228005630.GA15348@envy17> (mark gross's message of "Mon, 27 Feb 2012 16:56:30 -0800") Sender: cpufreq-owner@vger.kernel.org To: markgross@thegnar.org Cc: Kevin Hilman , "len.brown@intel.com" , "cpufreq@vger.kernel.org" , "linux-pm@lists.linux-foundation.org" , "j-pihet@ti.com" , davej@redhat.com, pavel@ucw.cz, rjw@sisk.pl List-Id: linux-pm@vger.kernel.org Adding people that were part of the thread in the beginning.. mark gross writes: > On Mon, Feb 27, 2012 at 04:04:00PM +0100, Antti Miettinen wrote: >> To the lists too.. >> >> On 02/27/2012 04:49 PM, Kevin Hilman wrote: >> > mark gross writes: >> > >> > >> Current QoS settings could be thought of as performance constraints >> > >> too. It's just that they determine minimum performance. Adding >> > >> constraints for maxium performance is not a big stretch in my mind. >> > > >> > > Its not a big stretch to me either. I just think its a bit of a hack >> > > and there is a bigger more interesting issue getting overlooked. >> > > >> > > Lastly why not simply make cpufreq thermal aware and talk directly to >> > > it if you even need too? >> > >> > In fact, making a thermal framework "cooling device" that talks directly >> > to CPUfreq is already what's being done by the Linaro PMWG folks. >> > >> > The problem is that CPUfreq only controls the CPU frequency. >> > >> > There are other devices that could be scaled back to reduce heat as well >> > (DSP, and especially GPU), so having a more generic per-device >> > constraint interface that can cap the frequency for *any* scalable >> > device is a better framework IMO. >> > >> > It just so happens that pm_qos is already a good per-device constraint >> > framework and can easily modified to cap performance as well as request >> > a minimum performance. >> > >> > Kevin > > ok I'll stop trying to block it. > > I want to re-do the whole works anyway. If this helps in the mean time > then go for it. Great :-) So what do other people think? Could we merge global CPU frequency constraints for now? I agree that more work is needed for e.g. per CPU constraints, user space interface and more complete thermal management. Actually for future I think the constraints could also become more general than just min/max "reduction operators". For e.g. core online status you might want union/intersection of bitmaps. Also, the more complete thermal management is related to load management in general (power budgeting for other reasons than just thermal). --Antti