| From: Pavel Machek<pavel at ucw.cz> | | Hi! | | On Thu 2006-08-31 16:44:12, Amit Kucheria wrote: | > On Thu, 2006-08-31 at 00:36 +0200, ext Pavel Machek wrote: | > > On Wed 2006-08-30 14:00:53, Amit Kucheria wrote: | > > > But PowerOP would allow SoC-based systems to tune the operating points | > > > to get the most out of their top-10 use-cases and sleep modes. | > > | > > Question is: can we get similar savings without ugly interface powerop | > > presents? | > | > If I have understood correctly, your main objection is to defining new | > operating points from userspace? | | Well, that is big objection, but not my main one. I believe that "new | operating points from userspace" are non-starter. "So obviously wrong | that noone would merge that". --- Why? Are you interpreting "from user space" as "under user control"? A lot of us have been taught for some time that it's a good thing to move stuff out of the kernel, unless it really needs to be there. Is there some reason, in your perception, why definition of operating points really needs to be in the kernel? Definition of the operating points, as opposed to changing from one OP to another, shouldn't have any timing issues, so why isn't a privileged user-space manager a reasonable approach? --- | | > The only other interface is the actually setting of a (named) operating | > point and that is _required_ to do anything useful. | | No, they are not. | | We already have interface for selecting cpu frequency. Lets keep it. --- As noted previously, OPs bundle together more than just the frequency. Those of us supporting the OP model believe that you can't intelligently change CPU frequency in isolation and you can't change some of those parameters independently, because only certain combinations work. --- | ... | Now, it should be up-to the powerop framework to select best operating | point given "cpu speed, dsp speed, usb on/off" state. But I argue that | this should be done in-kernel and hidden from user. --- Well, I agree with hiding it from the user, but there's no particular reason that means it needs to be done in the kernel. Again, we like to have it run from user-space, so we can replace it easily (without recompiling/restarting the kernel) in development. scott -- scott preece motorola mobile devices, il67, 1800 s. oak st., champaign, il 61820 e-mail: preece at motorola.com fax: +1-217-384-8550 phone: +1-217-384-8589 cell: +1-217-433-6114 pager: 2174336114 at vtext.com
