Re: [boost] [threadpool] parallel_sort example

Subject: Re: [boost] [threadpool] parallel_sort example
From: vicente.botet (vicente.botet_at_[hidden])
Date: 2009-03-02 16:59:59

----- Original Message ----- 
From: <k-oli_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Monday, March 02, 2009 10:05 PM
Subject: Re: [boost] [threadpool] parallel_sort example

> 
> Am Sunday 01 March 2009 22:53:14 schrieb vicente.botet:
> 
>> Oliver you are free to take this as example for the ThreadPool
>> documentation, if you consider this can improve the understanding of what
>> can be done with your library.
> 
> Hi Vicente,
> I've executed your parallel_sort2.cpp with NN = 10000000 on a core 2 duo E6600 
> (with  BOOST_BIND_WORKER_TO_PROCESSORS, BOOST_DISABLE_ASSERTS and -02)
> 
> std::sort: reverse 0..10000000 158 milli seconds
> std::sort: 0..10000000 148 milli seconds
> boost::sort: reverse 0..10000000 158 milli seconds
> boost::sort: 0..10000000 148 milli seconds
> parallel_sort 5000000:  reverse 0..10000000 145 milli seconds
> parallel_sort 5000000:  0..10000000 121 milli seconds
> parallel_sort 2500000:  reverse 0..10000000 169 milli seconds
> parallel_sort 2500000:  0..10000000 148 milli seconds
> parallel_sort 1250000:  reverse 0..10000000 190 milli seconds
> parallel_sort 1250000:  0..10000000 166 milli seconds
> parallel_sort 625000:  reverse 0..10000000 201 milli seconds
> parallel_sort 625000:  0..10000000 184 milli seconds
> parallel_sort 312500:  reverse 0..10000000 216 milli seconds
> parallel_sort 312500:  0..10000000 203 milli seconds
> 
> I've added your example - thx.
> 

Just to comment some variations

With 4 threads I get the following results:

std::sort: reverse 0..400000 37 milli seconds
std::sort: 0..400000 35 milli seconds
boost::sort: reverse 0..400000 36 milli seconds
boost::sort: 0..400000 34 milli seconds
parallel_sort 200000:  reverse 0..400000 39 milli seconds
parallel_sort 200000:  0..400000 22 milli seconds
*parallel_sort 100000:  reverse 0..400000 26 milli seconds
*parallel_sort 100000:  0..400000 26 milli seconds
parallel_sort 50000:  reverse 0..400000 30 milli seconds
parallel_sort 50000:  0..400000 28 milli seconds
parallel_sort 25000:  reverse 0..400000 30 milli seconds
parallel_sort 25000:  0..400000 32 milli seconds

With 6 threads
std::sort: reverse 0..400000 40 milli seconds
std::sort: 0..400000 36 milli seconds
boost::sort: reverse 0..400000 36 milli seconds
boost::sort: 0..400000 39 milli seconds
parallel_sort 200000:  reverse 0..400000 43 milli seconds
parallel_sort 200000:  0..400000 21 milli seconds
* parallel_sort 100000:  reverse 0..400000 25 milli seconds
* parallel_sort 100000:  0..400000 31 milli seconds
 parallel_sort 50000:  reverse 0..400000 31 milli seconds
 parallel_sort 50000:  0..400000 30 milli seconds
 parallel_sort 25000:  reverse 0..400000 30 milli seconds
 parallel_sort 25000:  0..400000 30 milli seconds

These results seems extrange to me for an algorith that do not have IO, and no synchronization between tasks.

Vicente