Re: [Boost-users] Xcode - Slow

Subject: Re: [Boost-users] Xcode - Slow
From: Raphaël Amiot (raphael.amiot_at_[hidden])
Date: 2010-06-30 13:12:15

Code here. You'll need to change the path to boost headers in the includes to make it run.

Part that runs way too slow:

chrono.begin();
        for(int i=0; i<nombremult; i++)
        res = prod(m,n);
        
                if(chrono.elapsed()<1000)
                        fileoutput << chrono.elapsed() <<  "	" << chrono.elapsed_micro() << "	";
                else
                        fileoutput << chrono.elapsed() <<  "	" << 0 << "	";
                
        }

This goes far faster on visual than on xcode.

Le 30 juin 2010 à 18:09, Christopher Jefferson a écrit :

> 
> On 30 Jun 2010, at 16:55, Raphaël Amiot wrote:
> 
>> Hello there.
>> 
>> I am implementing matrix multiplication and am trying to have my stuff run as fast as possible.
>> But then I noticed something strange. 
>> Using Xcode,
>> 
>> resultmatrix = prod(matrix1,matrix2);
>> 
>> is 10 to 16 times slower (with 100x100 matrixes) than simply doing something like that: 
>> 
>> 
>> for(...)
>> 	for(...)
>> 		for(..)
>> 			multiply_things();
>> 
>> And 20 to 40 times slower than a simple threaded approach.
>> 
>> 
>> Using visual studio, it's 2 times faster than naive multiplication.
>> 
>> 
>> This is on a release build, with 
>> #define BOOST_UBLAS_NDEBUG 1
>> #define NDEBUG 1
>> 
>> So what gives?_______________________________________________
> 
> Could you provide a small complete program which shows your problem?
> 
> Chris
> 
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