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None Re: Surprisingly poor performance of Geant4.9.2.p01 on a bi-quad-core Intel xeon machine 

Forum: Installation and Configuration
Re: Question Surprisingly poor performance of Geant4.9.2.p01 on a bi-quad-core Intel xeon machine
Re: None Re: Surprisingly poor performance of Geant4.9.2.p01 on a bi-quad-core Intel xeon machine (Paul Nicholas Colin Gloster)
Re: None Re: Surprisingly poor performance of Geant4.9.2.p01 on a bi-quad-core Intel xeon machine
Date: 21 Sep, 2009
From: Paul Nicholas Colin Gloster <Paul Nicholas Colin Gloster>

On Mon, 21 Sep 2009, yong.kong@icxt.com submitted:

|------------------------------------------------------------------------|
|"> Hello,                                                               |
|>                                                                       |
|> You have made it clear that the newer system was using a 64bit        |
|> operating system and that the older system was using a 32bit operating|
|> system. 32bit executables can be faster than 64bit                    |
|> executables. However, you did not provide enough evidence to          |
|> conclusively deduce that the wordlength accounts for your observations|
|> because:                                                              |
|> * you have not made it clear that both sets of measurements were for  |
|>   Geant4.9.2.p01;                                                     |
|> * the Linux kernels do not differ merely by wordlength: they are      |
|>   2.6.30-gentoo-r4 and 2.6.24-gentoo-r8;                              |
|> and                                                                   |
|> * other potentially influential factors have been left unreported,    |
|>   such as the compilers used; and the Geant configuration options used|
|>   when compiling and installing Geant.                                |
|>                                                                       |
|> Yours sincerely,                                                      |
|> Nicholas Paul Colin Gloster                                           |
|>                                                                       |
|                                                                        |
|Hi,                                                                     |
|                                                                        |
|The compiler used is gcc-4.1.2 in both machines. The same configuration |
|option from Linux-g++ were used. For the quad-core machine I also tried |
|to change the compiler ( gcc-3.4.6, 4.1.2 and 4.3.3) and options (like  |
|-mtune=native -msse4.1), but the results are almost the same.           |
|                                                                        |
|I also tried to compile my Geant4 application by using mpicxx and then  |
|ran the executable with a single thread, but nothing gets better.       |
|                                                                        |
|regards                                                                 |
|                                                                        |
|Yong"                                                                   |
|------------------------------------------------------------------------|

Hi,

You have checked a lot but there are still things which I mentioned
which you do not seem to have checked:

* have you installed the 32bit operating system on the newer machine
  and tried that instead of the 64bit operating system which you
  already tried?;
* are you using the same release of Geant on both machines?;
* how do the files $G4INSTALL/Configure differ on the different
  machines?;

Regards,
Paul Colin Gloster

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1 None: Re: Surprisingly poor performance of Geant4.9.2.p01 on a bi-quad-core Intel xeon machine   (icx719 - 21 Sep, 2009)
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