[Beowulf] Threaded code

Joe Landman landman at scalableinformatics.com
Tue Aug 17 13:26:21 EDT 2004


Art Edwards wrote:

>It is conceivable, but unlikely. Including blas3 in the build increases
>the speed of the code by a factor of 2-3. The jobs take either days or
>weeks.
>  
>

Do you mean Atlas increases speed by 2-3x?  Or simply the BLAS3 bits 
(non-Atlas)?  There are some BLAS3 libs running around in various 
distributions.  SuSE will happily install BLAS for you if you request 
it, in which case you need to worry about link order.

I would look at the output of ldd.  Make sure it is linking in the right 
code.  Next, while the code is running, do an

    ps -fjg

after starting he code in another window.  You should see stuff like 
this ...

crunch:/var/log/httpd # ps fjg
 PPID   PID  PGID   SID TTY      TPGID STAT   UID   TIME COMMAND
25381 25384 25384 25384 pts/7    27532 S        0   0:00 -bash
25384 27532 27532 25384 pts/7    27532 S        0   0:00  \_ tail -f 
mail auth
25242 25245 25245 25245 pts/4    29077 S        0   0:00 -bash
25245 29077 29077 25245 pts/4    29077 R        0   0:00  \_ ps fjg
24959 24962 24962 24962 pts/2    28718 S        0   0:00 -bash
24962 27588 27588 24962 pts/2    28718 S        0   0:04  \_ nedit 
login.html
24962 27618 27618 24962 pts/2    28718 S        0   0:00  \_ nedit 
../etc/bbs.ini
16116 16118 16118 16118 pts/1    23153 S        0   0:00 bash
16118 23153 23153 16118 pts/1    23153 S        0   5:26  \_ ping indy

Your threads will have different process IDs.

also try an

    ps fjma

and look for your process threads.

Joe

>Art
>
>On Tue, Aug 17, 2004 at 01:05:13PM -0400, Joe Landman wrote:
>  
>
>>Art:
>>
>> Is it possible that the parallel section completes very quickly?  Or 
>>that code path is not taken?
>>
>>Joe
>>
>>Art Edwards wrote:
>>
>>    
>>
>>>I mean that when we run the threaded code and look at top, don't see two
>>>processors running. The load is always less than or equal to one. When
>>>we run two separate jobs, we see a load of 2. 
>>>
>>>Art Edwards
>>>
>>>On Tue, Aug 17, 2004 at 07:45:32AM -0700, Alvin Oga wrote:
>>>
>>>
>>>      
>>>
>>>>hi ya
>>>>
>>>>yup.. that is dual cpu
>>>>
>>>>On Tue, 17 Aug 2004, Art Edwards wrote:
>>>>
>>>>  
>>>>
>>>>        
>>>>
>>>>>We are running SuSE 9.1 on a system with 8 GB of ram and two scsi disks.
>>>>>Here is /proc/cpuinfo
>>>>>processor       : 0
>>>>>    
>>>>>
>>>>>          
>>>>>
>>>>good
>>>>
>>>>  
>>>>
>>>>        
>>>>
>>>>>processor       : 1
>>>>>    
>>>>>
>>>>>          
>>>>>
>>>>good
>>>>
>>>>  
>>>>
>>>>        
>>>>
>>>>>Linux bladerunner 2.6.4-52-smp #1 SMP Wed Apr 7 01:58:54 UTC 2004 x86_64
>>>>>x86_64 x86_64 GNU/Linux
>>>>>    
>>>>>
>>>>>          
>>>>>
>>>>good
>>>>
>>>>
>>>>  
>>>>
>>>>        
>>>>
>>>>>>Newbie question:
>>>>>>
>>>>>>We just purchased a dual opteron box that is running an SMP kernel. We
>>>>>>have built a fortran code using g77 and a pthreaded atlas. Currently, we
>>>>>>see only one processor. What really simple thing have we missed?
>>>>>>      
>>>>>>
>>>>>>            
>>>>>>
>>>>so what do you mean by "see only one processor" ??
>>>>
>>>>c ya
>>>>alvin
>>>>  
>>>>
>>>>        
>>>>
>>>
>>>      
>>>
>>-- 
>>Joseph Landman, Ph.D
>>Founder and CEO
>>Scalable Informatics LLC,
>>email: landman at scalableinformatics.com
>>web  : http://www.scalableinformatics.com
>>phone: +1 734 612 4615
>>    
>>
>
>  
>


-- 
Joseph Landman, Ph.D
Founder and CEO
Scalable Informatics LLC,
email: landman at scalableinformatics.com
web  : http://www.scalableinformatics.com
phone: +1 734 612 4615

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