Mark Haywood wrote: > >> I guess we already discussed this issue before? >> Turbo mode is exported as P0 = marked frequency + 1Mhz, >> but allow the processors to run faster so that the performance can >> be improved up to 20%. Average CPU frequency is doable by the >> hardware feedback mechanism. >> >> > > I think that Vinay was asking Jim about the RFE that he added to > http://www.opensolaris.org/os/project/tesla/Work/Powertop/ > > As I think you and I discussed on the alias earlier, the average CPU > frequency while in P0 can be determined by strategically placing > APERF/MPERF value dtrace probes when transitioning to and from P0. At > least that would be the first thing I'd try ... > We were chatting about this yesterday, and I was wondering what happens if we stay at P0 long enough to where APERF/MPERF could wrap? Is that a concern...or is the time it would take the counters to wrap sufficiently long? I haven't looked in detail yet, but I was also wondering if there's a way to explicitly reset the counters at the beginning of a sampling interval to maximize the time-to-wrap (if it is short).
Thanks, -Eric
