Vinay Devadas wrote: >> P0 is not equal to turbo mode. P0 means the system is requesting to >> the speed of the max performance. When Turbo mode is enabled, P0 give >> the system a chance to go into turbo mode, but whether the processor >> enter turbo mode or not is determined by the hardware. So, even if >> APERF/MPERF may be < 1, if DTrace says we are in P0, we should let >> PowerTOP and users know the system is requesting max performance >> speed, not max non turbo speed. > > I agree with what you say above, but I am sorry I need more > clarification on the display issue. > > Now say max non-turbo frequency is 2400 and P0 is 2401 as > displayed by powertop. PowerTop does not diplay P0, P1 ... > etc. It only displays frequencies 2000, 2400, 2401 etc. i.e. > the display is something like, > P-state Frequency > 2000 > 2400 > 2401 > > Now considering your case, let us say IDA is enabled and > Dtrace says we are in P0. CURRENTLY powertop display 100% in > 2401. However, sampling the APERF/MPERF values, if the ratio > <=1 we are running at 2400 MHz (*I agree in P0, but it is 2400 > and NOT 2401*). If the ratio is larger than one, then we are > running at some frequency higher than 2400Hz. > > This is precisely what I do. IDA enabled and APERF/MPERF <=1, > I display 100% next to 2400Mhz (This means we are in P0 and > running at 2400 Mhz). If APERF/MPERF > 1, I display AVERAGE > frequency instead of *2401 Mhz* and the *time spent there*. > Just because IDA is enabled will it not be incorrect to > display 100% next to 2401 just because Dtrace probe tells we > are in P0 as powertop does currently ? >
The frequencies is designated as P-state level. If powertop display 100% at 2400Mhz, how could the users know it's in P0 or P1? And When APERF/MPERF < 1 in P0, the actual speed may < 2400 due to T-state or hardware temperature limitation. why put it in 2400 statistics? The frequencies here are P0,P1, ... Pn. I understand you want to show the actual speed, but doing it just in P0 may make more sense. Another thing comes in my mind is, if the acutal speed 2400< P0 < 2401, let's display 2401 as well. An increment < 1Mhz is meaningless. Let's set the resolution of P-state frequency to 1Mhz. Thanks, -Aubrey
