On Thu, 2006-08-17 at 21:40 +0000, ext Pavel Machek wrote: > > The userspace interface in Eungeny's patches is for other userspace > > programs (policy managers) to activate/deactivate valid operating points > > in the system dynamically and if necessary, introduce new ones into the > > system. It will also allow the operating points to be referenced by name > > instead of the tuple. > > > > Then, we will be able to use names like 'video', 'mp3', 'fast', > > 'powersave', 'usb' to switch to the relevant operating point based on > > configuration of the policy manager. > > This seems to be too specific to embedded machine. > > If userspace wants to work with usb and play mp3s at the same time, > what does it do? Switch to 'fast'? The operating point for a use-case specifies the _minimum_ required for the use-case. You can always go up. The system designer is responsible for 'designing' operating points that take into account multiple use-cases. Designing here refers to mapping use-cases to HW operating points. Consider an example system with a main CPU and a DSP. To simplify discussion, lets assume 3 levels for CPU and DSP speeds and system voltage. Then, here is what an example operating-point to use-case mapping table could look like: # CPU speed DSP speed Voltage use-case ---------------------------------------------------------- 1. high high high fast, video 2. med high high 3. med med med usb[1] 4. low med med mp3 5. low low low powersave [1] USB has voltage constraint (voltage >= med) Mapping ======= Performance related: fast, video, mp3 Power related: powersave Miscellaneous: usb - Now if we are playing mp3, we switch to OP 4. - Add usb and we switch to OP 3. - Now our performance monitor (e.g load avg) indicates that we need more CPU processing. So we switch to OP 2. Regards, Amit -- Amit Kucheria <amit.kucheria at nokia.com> Nokia
