Re: [Algorithms] Timing problems

[Jan W. <jan...@gm...>]

> On a modern version of Windows, with proper motherboard and CPU drivers,
> QPC will use that same timer, so you don't need any custom driver.
Yes, but as mentioned in the accompanying article (excerpt follows), HPET  
support hasn't been backported to Windows XP, which means many existing  
systems otherwise lack a decent timer.

>>
In the mean time, since Windows does not offer
a ubiquitous software solution, the TSC is not reliable. In an unfortunate
twist, it is precisely this timer that QPC uses on such dual-core  
platforms.
One can force it to use the PMT by adding /usepmtimer to boot.ini [QPC
Workaround], but making changes to such a critical system file should not
be asked of users. Finally, despite Microsoft having issued the HPET spec-
ification 5 years ago, support for it has not been patched into Windows XP
and it is only available on Vista.

These circumstances result in the moribund state of affairs that was previ-
ously described: on many systems today, only a mere millisecond-resolution
timer is available. According to [Valve Survey], 93% of the participating
systems are running Windows XP, and 22% have more than one processor
or core. This large proportion cannot be ignored, so we will have to find a
workaround for the above issue.
<<

Best Regards
Jan