On Sun, Apr 12, 2009 at 9:16 AM, Phillip Wagstrom -- Area Technical Engineer <[email protected]> wrote: > Jürgen Keil wrote: >>> >>> I noticed a similar issue on my Tecra M5 when going from builds 109 to >>> builds 110 and 111. powertop would say that the cpu would be running at >>> 1GHz but kstat would stay it was still at 1830000000 >>> I stumbled upon an internal Solaris Nevada bug (CR# 6818514) that was >>> created for ATOM processors showing the same thing that suggests using: >>> >>> cpupm enable poll-mode >>> >>> Setting this on my M5 seems to cause the CPU to cycle down as expected. >> >> Hmm, my ASUS N4L-VM DH Core2Duo box shows the same. >> >> Seems to be a feature (or a bug?) of the new >> "Power Aware Dispatcher" (PAD) support that >> was added in build 110. >> >> http://www.opensolaris.org/os/project/tesla/Work/CPUPM/ >> >> Maybe with the new PAD support (cpupm enabled in >> "event-mode") the kernel is able to switch back to the >> highest cpu frequency *much* faster (=> event driven), >> so that "kstat cpu_info:::current_clock_Hz" now always >> reports the highest cpu frequency? >> >> (That is, monitoring the kstat cpu_info >> current_clock_Hz isn't valid any more to find out >> if cpu power management is working -- use powertop >> instead) > > I wasn't aware of PAD. Looking at powertop, I did see that the CPU > frequency was switching there, though it was always at the max according to > kstat (even when sitting completely idle). What you suggest could very well > be the case. > I just happened to notice it since my laptops fan was running more > often. I guess that I'll have to monitor how long the battery lasts between > the different modes. > > -Phil >
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. Thanks, -Aubrey _______________________________________________ opensolaris-discuss mailing list [email protected]
