Re: [boost] very poor thread performance

From: Maik Beckmann (beckmann.maik_at_[hidden])
Date: 2008-05-14 17:31:54

Am Mittwoch 14 Mai 2008 23:14:47 schrieb James Sutherland:

> Okay, then I am interpreting things correctly, and my internal timer
> seems to be consistent with the output of the "time" command that you
> refer to.  To restate, the sum of "real" and "system" time is the
> pertinent measure.  The results you posted then indicate that there is
> no speedup associated with increasing the number of threads.  I am now
> seeing the same thing...
>
> So any thoughts as to why there is no speedup?

real: the real time it took
user: CPU time owned by the user it took
sys: CPU time owned by the system it took

Thus this timings:

$time ./a.out
Executing 12 tasks using 1 threads.
time: 9.64

real    0m9.668s
user    0m9.641s
sys     0m0.004s

$ time ./a.out
Executing 12 tasks using 2 threads.
time: 9.91

real    0m4.991s
user    0m9.909s
sys     0m0.012s

===
0m9.668s vs.  0m4.991s

say that the 2-thread version is about two times faster than the single 
threaded version.

Best,
-- Maik