time.clock() or Windows bug?
Theo v. Werkhoven
theo at van-werkhoven.nl.invalid
Sun Jun 8 22:57:00 CEST 2008
The carbonbased lifeform Nick Craig-Wood inspired comp.lang.python with:
> Theo v. Werkhoven <theo at van-werkhoven.nl.invalid> wrote:
>> Sample 1, at 0.0 seconds from start; Output power is: 8.967 dBm
>> Sample 17, at 105.7 seconds from start; Output power is: 9.147 dBm
>> Sample 18, at 112.4 seconds from start; Output power is: 9.284 dBm
>> Sample 19, at 119.0 seconds from start; Output power is: 9.013 dBm
>> Sample 20, at 125.6 seconds from start; Output power is: 8.952 dBm
>> Sample 21, at 91852.8 seconds from start; Output power is: 9.102 dBm
>> Sample 22, at 91862.7 seconds from start; Output power is: 9.289 dBm
>> Sample 23, at 145.4 seconds from start; Output power is: 9.245 dBm
>> Sample 24, at 152.0 seconds from start; Output power is: 8.936 dBm
>> But look at the timestamps of samples 21, 22 and 43.
>> What is causing this?
>> I've replaced the time.clock() with time.time(), and that seems to
>> solve the problem, but I would like to know if it's something I
>> misunderstand or if it's a problem with the platform (Windows Server
>> 2003) or the time.clock() function.
> time.clock() uses QueryPerformanceCounter under windows. There are
> some known problems with that (eg with Dual core AMD processors).
> See http://msdn.microsoft.com/en-us/library/ms644904.aspx
> And in particular
> On a multiprocessor computer, it should not matter which processor
> is called. However, you can get different results on different
> processors due to bugs in the basic input/output system (BIOS) or
> the hardware abstraction layer (HAL). To specify processor
> affinity for a thread, use the SetThreadAffinityMask function.
Alright, that explains that then.
> I would have said time.time is what you want to use anyway though
> because under unix time.clock() returns the elapsed CPU time which is
> not what you want at all!
You're right, using fuctions that do not work cross platform isn't
Cheers for the explanation Nick
theo at van-werkhoven.nl ICQ:277217131 SuSE Linux
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