[ntp:questions] NTP client with ability to write Windows NT system time to hardware clock?

David J Taylor david-taylor at blueyonder.co.uk.invalid
Tue Jan 4 11:08:27 UTC 2011


> Hm, I recently found that at least under Windows Server 2008 x64 the
> QueryPerformanceCounter (QPC) call is obviously emulated when running 32
> bit applications on this 64 bit system.
>
> My wclkres program (32 bit binary)
> http://www.meinberg.de.www/download/utils/windows/wclkres-1.4.zip
> reports a QPC frequency of 2.341 MHz and a thus a resolution of 427 ns 
> only.
> The mean execution time of a QPC call is about 64 ns, so subsequent QPC
> calls often return the same values.
>
> So maybe native 64 bit binaries would yield better results than 32 bit
> binaries on an x64 system.
>
>
> Regards,
>
> Martin
> -- 
> Martin Burnicki

Martin,

Some extra reference points for you - I just checked on a couple of 
Windows-7 64-bit systems:

Intel D330 Atom PC (Molde):
QPC: 1.563 MHz, 51ns
(my own software shows 26ns for a GetTickCount call, and 51ns for QPC)

Intel i5-760 PC (Alta)
QPC: 2.744 MHz, 33ns
QPC: 2.744 MHz, 15ns (second run)
(my own software shows 6ns for a GetTickCount call, and 12ns for QPC)

Cheers,
David 




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