"Martin Burnicki" <[email protected]> wrote in message
news:[email protected]...
[]
AFAIK if the TSC is used then the clock frequency reported for QPC
matches
the CPU's clock full clock frequency, and IIRC then according to some MS
docs the reported frequency does not even change when the CPU's clock is
decreased for power saving. IMO that also wouldn't make much sense.
From what I've seen the reported QPC clock frequency depends on which
timer
circuit is being used. Some months ago I've already posted what I had
found:
http://lists.ntp.org/pipermail/questions/2009-March/022159.html
But of course I can not *guarantee* this is always correct ;-)
In that article there are also some hints which Windows versions /
service
packs use which timer to implement QPC. I've just reread that article
and
found this perfectly matches what Alan has observed, i.e. Windows XP SP3
should use the PM timer even if no /usepmtimer flag has been added in
Windows' boot.ini.
Of course it does not explain the problems Alan is observing.
Regards,
Martin
Thanks, Martin. I'm beginning to wish I'd never asked, as I have Windows
XP SP3 here and yet the performance counter is running at 2.4GHz (Intel
E6600 dual-core). Or does the PM_Timer only apply to AMD systems?
The AMD Vista and Windows-7 desktop systems show 3.579...MHz, an Intel
Windows-7 portable 1.757MHz (PIT?), an Intel Vista portable 14.3MHz
(HPET), and an Intel Windows Vista Desktop 14.3MHz.
All frequencies you listed, and nothing which helps Alan. Seemed to have
a peculiar timer resolutions though - I never seen 3.906 ms or 1.953 ms.
What software is setting those?
Cheers,
David
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