On Mon, Apr 27, 2009 at 5:16 AM, Matt Ingenthron <[email protected]> wrote: > Aubrey Li wrote: >> >> On Sun, Apr 26, 2009 at 9:44 PM, Mark Haywood <[email protected]> >> wrote: >> >>>> >>>> Should've been more specific in my reply, so: >>>> >>>> % vi /etc/power.conf # Change to poll-mode >>>> % pfexec pmconfig >>>> >>>> % pfexec powertop # shows proc. always at max speed % pfexec reboot # >>>> After the reboot, powertop shows proc. at lower freq. >>>> >>>> >>> >>> It is either a bug or your system isn't idle enough for poll-mode to >>> lower >>> the freq. either. I have successfully switched event-mode and poll-mode >>> many >>> times without a reboot. >>> >>> >> >> I checked it just now on my system(OpenSolaris200906-snv111), >> it works properly. When change to poll-mode, you'd better to set the >> "cpu-threshold" to "1s". The default scanning cycle is 15s, which means >> you need to wait for a while(>15s) to see the frequency transition. >> ============================ >> cpupm enable poll-mode >> cpu-threshold 1s >> ============================ >> After issue "pmconfig", you should see the lowest frequency residency >> in powertop if >> your system is idle. >> > > Some observations after some experimentation on my systems. All were done > with the system effectively 'idle'. X was up with a GNOME session, and > compiz was on, but most other apps that I usually run were down. I was > using gnome-terminal. > > If I switch to event-mode, powertop does occasionally, for a refresh, show > the pstate changing from something other than the highest frequency. > Observing it for a minute or so shows that it only happens maybe 10-20% of > the time. via mpstat 5, both cores show a median of about 97% idle (just > eyeball observations) > > In poll-mode with cpu-threshold set to 3s, I see the pstate changing much > more frequently. I also see pstates other than just the highest frequency > and the lowest frequency. > Like others have observed, powertop only ever shows me the 100% in any one > pstate. I believe that's where someone mentioned a bug.
Yes, As Mark pointed, it's a known bug: http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6829404. > So I guess my question is, how should I get data to know if my usage > pattern/system is best in event-mode or poll-mode? Two big differences between event-mode and poll-mode: 1. response latency. event-mode response much more quick than poll-mode. frequency transition in the poll-mode is periodical and the time is specified by "cpu-threshold", while in the event-mode, the transition occurs in the thread switching, much more sensitive than the poll-mode. 2. transition condition. poll-mode is using cpu utilization while event-mode is using cmt utilization. event-mode also installs two governors to avoid transient load and transient idle. That means in event-mode: 1) very light load could generate frequency transition. 2) persistent load will not generate frequency transtion. So, if the load prefers the % cpu utilization, poll-mode is more reliable. Thanks, -Aubrey _______________________________________________ indiana-discuss mailing list [email protected] http://mail.opensolaris.org/mailman/listinfo/indiana-discuss
