From mboxrd@z Thu Jan  1 00:00:00 1970
From: michel.dagenais@polymtl.ca (Michel Dagenais)
Date: Thu, 11 Nov 2010 14:23:50 -0500
Subject: [ltt-dev] Experiments on CPU time statistics
In-Reply-To: <20101111185944.GA27102@Krystal>
References: <20101111125029.18064gu6bt6eo084@www.usherbrooke.ca>
	<20101111185944.GA27102@Krystal>
Message-ID: <4CDC42C6.5030109@polymtl.ca>


>> time statistics:
>> real	0m10.715s
>>
>> user	0m0.420s
>>
>> sys	0m6.350s
...
> Elapsed time is the total of the per-thread elapsed time I think (it's
> really been a while since I played with this code though). It would make
> sense if you have 54 threads in your system.
>
> I don't have entire confidence that the elapsed time is correct.

As a side note, while the elapsed time provided by "time" is probably 
reliable, the user and system time are obtained by sampling under 
asumptions which are sometimes not met. Arbitrarily large deviations 
from the reality are possible. The CPU time computed from the LTTng 
trace data is exact, not statistical.