[reSIProcate] Timer vulnerability

Alan Hawrylyshen alan at jasomi.com
Tue Apr 12 11:37:40 CDT 2005


On Apr 9, 2005, at 09.27, Scott Godin wrote:

> I think it would be better to add some relative time functions to 
> Timer and
> have the timers use these, instead of redefining getSystemTime().  I 
> was
> considering do this a while back - but the consensus was to not worry 
> about
> it.  Looks like you found another reason to do it - so maybe it's 
> time!  : )
> Do Unix OSs have a function similar to GetTickCount()?
>

One of the BIG problems with GetTickCount and families is that they no 
longer produce monotonically increasing results.
On devices with Intel SpeedStep technology (for example) or other power 
management technologies, the TickCount can move in very unpredictable 
ways. This results is wildly inaccurate timers. Care must be taken to 
select a replacement (if done) that does not make use of a fundamental 
that varies non-linearly.  On a plus side, we can get rid of any direct 
calls to time() since having a contained Time utility class is a Good 
Thing™.

Alan

a l a n a t j a s o m i d o t c o m




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