Performance degrades for more than 2 threads on Xeon X5355

Posted by zoolii on Server Fault See other posts from Server Fault or by zoolii
Published on 2010-02-15T09:01:53Z Indexed on 2010/03/20 14:01 UTC
Read the original article Hit count: 320

Filed under:

multi-core

Hi All,

I am writing an application using boost threads and using boost barriers to synchronize the threads. I have two machines to test the application.

Machine 1 is a core2 duo (T8300) cpu machine (windows XP professional - 4GB RAM) where I am getting following performance figures :

Number of threads :1 , TPS :21

Number of threads :2 , TPS :35 (66 % improvement)

further increase in number of threads decreases the TPS but that is understandable as the machine has only two cores.

Machine 2 is a 2 quad core ( Xeon X5355) cpu machine (windows 2003 server with 4GB RAM) and has 8 effective cores.

Number of threads :1 , TPS :21

Number of threads :2 , TPS :27 (28 % improvement)

Number of threads :4 , TPS :25

Number of threads :8 , TPS :24

As you can see, performance is degrading after 2 threads (though it has 8 cores). If the program has some bottle neck , then for 2 thread also it should have degraded.

Any idea? , Explanations ? , Does the OS has some role in performance ? - It seems like the Core2duo (2.4GHz) scales better than Xeon X5355 (2.66GHz) though it has better clock speed.

Thank you

-Zoolii

Performance degrades for more than 2 threads on Xeon X5355

Posted by zoolii on Stack Overflow See other posts from Stack Overflow or by zoolii
Published on 2010-02-15T09:01:53Z Indexed on 2010/03/20 16:21 UTC
Read the original article Hit count: 320

Filed under:

multi-core

Hi All,

I am writing an application using boost threads and using boost barriers to synchronize the threads. I have two machines to test the application.

Machine 1 is a core2 duo (T8300) cpu machine (windows XP professional - 4GB RAM) where I am getting following performance figures :

Number of threads :1 , TPS :21

Number of threads :2 , TPS :35 (66 % improvement)

further increase in number of threads decreases the TPS but that is understandable as the machine has only two cores.

Machine 2 is a 2 quad core ( Xeon X5355) cpu machine (windows 2003 server with 4GB RAM) and has 8 effective cores.

Number of threads :1 , TPS :21

Number of threads :2 , TPS :27 (28 % improvement)

Number of threads :4 , TPS :25

Number of threads :8 , TPS :24

As you can see, performance is degrading after 2 threads (though it has 8 cores). If the program has some bottle neck , then for 2 thread also it should have degraded.

Any idea? , Explanations ? , Does the OS has some role in performance ? - It seems like the Core2duo (2.4GHz) scales better than Xeon X5355 (2.66GHz) though it has better clock speed.

Thank you

-Zoolii

Developer IT