You can write 0 to clear it.. actually that's part of what you do even after taking a sample.
Cheers, ashok raj - Open Source Technology Center >-----Original Message----- >From: tesla-dev-bounces at opensolaris.org [mailto:tesla-dev-bounces at opensolaris.org] On Behalf Of Eric >Saxe >Sent: Friday, June 20, 2008 10:30 AM >To: Mark Haywood >Cc: Vinay Devadas; Jim.Britton at Sun.COM; tesla-dev at opensolaris.org >Subject: Re: [tesla-dev] Turbo Mode Support for Solaris > >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 >_______________________________________________ >tesla-dev mailing list >tesla-dev at opensolaris.org >http://mail.opensolaris.org/mailman/listinfo/tesla-dev
