Some performance numbers with different Allocators

Abhi abhi@qualcomm.com
Tue Jul 22 23:52:00 GMT 2003


Hi,
	I ran some performace tests using different allocators.
	The sample code is pretty simple,
	- it creates 4 threads
	- Each thread creates a list of string using an allocator
	- Adds 1000000 strings to the list in a for loop
	- Reads all these strings in a for loop
	- Modifies all these strings in a for loop

I ran this code 4 times (using 4 different allocators )
malloc = An allocator that uses malloc
malloc_hoard = An allocator that uses malloc with hoard (using
	       LD_PRELOAD, www.hoard.com)
STL = Default STL allocator that comes with gcc 3.4
		(pool allocator)
STL MT = MT STL allocator that comes with gcc3.4

Test Machine
Dual CPU, Linux Redhat 7.3, GCC3.4 snapshot

Here are the numbers
#CPU malloc		 malloc_hoard    STL                STL MT

1  31.280u 1.500s	 19.670u 0.900s  26.510u 13.470s    23.010u 4.330s
2  40.850u 2.270s	 38.630u 0.710s  103.820u 148.150s  51.600u 23.660s	

Seems like for this case hoard behaves the best, although a dual CPU
machine still performs worse that a single CPU machine for a MT
application. Does this seem surprising?

Also I guess this code is MT-safe, especially the malloc 
allocators...right? Just want to be sure!

Heres the code
----------------------------------------------------------------------
#include <list>
#include <pthread.h>
#include <errno.h>      // ETIMEDOUT
#include <string>
// For malloc
// #include <ext/malloc_allocator.h>
// #include <bits/allocator_traits.h>
// For MT
// #include <ext/mt_allocator.h>
// #include <bits/allocator_traits.h>


using namespace std;

// For Malloc
// typedef __allocator<char, __gnu_cxx::__malloc_alloc<0> >    MyAlloc;
// typedef basic_string<char, char_traits<char>, MyAlloc>      MyString;
// typedef std::list<MyString, __gnu_cxx::__malloc_alloc<1> >  List1;

// For MT
// typedef __allocator<char, __gnu_cxx::__mt_alloc<0> >    MyAlloc;
// typedef basic_string<char, char_traits<char>, MyAlloc>      MyString;
// typedef std::list<MyString, __gnu_cxx::__mt_alloc<1> >  List1;


// For Default STL
typedef string MyString;
typedef std::list<MyString> List1;



extern "C" void* Run(void *)
{
    List1 List;
    for ( int i=0; i<1000000; ++i )
    {
	MyString s;
	s.append("Hoiiiiiii");
	List.push_back( s );
    }

    for (List1::iterator j = List.begin(); j != List.end(); ++j)
    {
	MyString s = *j;
    }

    for (List1::iterator j = List.begin(); j != List.end(); ++j)
    {
	MyString s("Hiiiiiii");
	*j = s;
    }


}


using namespace std;

int main ()
{
    pthread_t  t1, t2, t3, t4;
    pthread_create(&t1,  // Thread Id for new thread
		   NULL,          // Thread attributes
		   Run,        // Function
		   NULL);

    pthread_create(&t2,  // Thread Id for new thread
		   NULL,          // Thread attributes
		   Run,        // Function
		   NULL);

    pthread_create(&t3,  // Thread Id for new thread
		   NULL,          // Thread attributes
		   Run,        // Function
		   NULL);

    pthread_create(&t4,  // Thread Id for new thread
		   NULL,          // Thread attributes
		   Run,        // Function
		   NULL);

    int errNum = pthread_join(t1, NULL);
    errNum = pthread_join(t2, NULL);
    errNum = pthread_join(t3, NULL);
    errNum = pthread_join(t4, NULL);
}

----------------------------------------------------------------------

Any Insights/Ideas
Thanks
....Abhi



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