[ntp:questions] micro-optimization
Martin Burnicki
martin.burnicki at meinberg.de
Thu Mar 12 08:59:00 UTC 2009
Augustine wrote:
> On Mar 11, 4:19 am, Terje Mathisen <"terje.mathisen at tmsw.no">
> wrote:
>>
>> I do know that Intel intends to make processor-based timers more useful
>> by setting up a counter which always runs at a fixed rate, independent
>> of any frequency power stepping. On such a cpu RDTSC would again be the
>> best choice, but hopefully the OS would realize this and start to use it
>> for QPC.
>
> What both Intel and AMD did on Core2 and Phenom was to move the "TSC"
> over to the BU. Therefore, RDTSC latency grew to typically 60 to 100
> cycles with, and this is worse for NTP, jitter, because of the
> different clock domains involved.
That's interesting.
Do you have some pointers where this is explained?
Martin
--
Martin Burnicki
Meinberg Funkuhren
Bad Pyrmont
Germany
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