On Mon, Apr 13, 2009 at 12:32 AM, Jürgen Keil <[email protected]> wrote: >> Frequency transition now occurs during the thread switching if the >> cmt_utilization >> of the power active domain think it's necessary. >> It's(event-mode) much more sensitive than before(poll-mode), even "kstat | >> grep >> current_clock_Hz" is possible to trigger a frequency transition. So, now, >> powertop >> is more reliable to report the cpu frequency utilization. > > The "P-states (frequencies)" statistic of powertop is showing > four entries (996, 1328, 1660 and 1992 MHz on a C2D T7200), > and I see either 100% at 996 Mhz, or 100% at 1992 MHz. > > That it doesn't use the 1328 and 1660 Mhz frequencies > is already reported as bug 6808377 "event based CPUPM > could leverage mid range speeds".
Yeah, exactly by the current design. > > But why is it always reporting a frequency usage split for 996 > and 1992 MHz as 100% - 0% (or 0% - 100%) ? Somehow it > doesn't make sense that in event-mode (according to powertop) > the cpu is always running at the slowest (highest) speed during > the 5 second powertop sample interval. I attached a dtrace probe for your interest, which is exactly what powertop is currently using. I actually saw some mid value on the 16 logical cores system. >From the script, you can see that the pstate transition occurs indeed. But mostly the percent is too small to be a mid value. As I mentioned, cmt_utilization is the major factor to drive pstate, not the cpu utilization, so what we got is expected. There certainly is an opportunity here. Thanks, -Aubrey
pstate.d
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