Re: Profiling Pipeline [was Re: [RT] Unit testing and CocoonUnit]

[Thor Heinrichs-Wolpert]

If you try to profile on a Unix environment based on timings you have 
to do multiple passes and get a statistical average to be meaningful.  
The timer functionality in the kernel or user space is at such a low 
priority that effectively it jumps between values ... that's why when 
tuning using tools like sar you have to set a decent sample size.  This 
is pretty much the case for any current non-realtime OS.  For long 
running tasks the time is probably OK, for small times ( < 10 ms  or 
even .1s timings ) on a busy system the times are just erroneous.

Cheers,
Thor HW
On 3-Nov-03, at 9:36 AM, Nicola Ken Barozzi wrote:

Berin Loritsch wrote:
...
I have a feeling the timings are useless largely because of the 
granularity
of the System.getTimeInMillis() method.  On Windows the granularity 
is 10 ms.
If the timing is less than that it registers as 0.  Add enough zeros 
and it
will always be less than the total time for the timing.
There is a way of getting around this by using JNI and calling the 
correct stuff. If you Google round you will sure find something. 
Probably there is something at www.javaworld.com.

--
Nicola Ken Barozzi                   [EMAIL PROTECTED]
            - verba volant, scripta manent -
   (discussions get forgotten, just code remains)
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