Re: Linux 2.4.18 Scheduler Bug?

[Nick Piggin <piggin@cyberone.com.au>]

Not that I know of unfortunately.

Vander Velden, Kent wrote:

>Thank you for your response.  I was affraid this might be the problem.
>Is there anything that we can do now, i.e. is there a SMP kernel does
>does consider priority?
>
>  Thanks.
>
>
>  
>
>>-----Original Message-----
>>From: Nick Piggin [mailto:piggin@cyberone.com.au]
>>Sent: Wednesday, September 17, 2003 10:48 PM
>>To: Vander Velden, Kent
>>Subject: Re: Linux 2.4.18 Scheduler Bug?
>>
>>
>>
>>
>>Vander Velden, Kent wrote:
>>
>>    
>>
>>>Please CC: responses to my email.
>>>
>>>On two seperate SMP machines I run two instances of two 
>>>      
>>>
>>different programs, minimin.x and random_simplex.  Both 
>>instances of random_simplex are niced to 20 on both machines. 
>> Both minimin.xand random_simplex are CPU bound processes.  
>>On the first machine the processes are allocated CPU as would 
>>be expected (data taken from 'top'):
>>    
>>
>>>
>>>Linux cn103 2.4.18-18.8.0smp #1 SMP Wed Nov 13 23:11:20 EST 
>>>      
>>>
>>2002 i686 i686 i386 GNU/Linux
>>    
>>
>>>
>>> PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME COMMAND
>>>
>>>25911 f459659   25   0  3452 3452  1032 R    94.3  0.1 
>>>      
>>>
>>167:13 minimin.x
>>    
>>
>>>25903 f459659   25   0  3604 3604  1072 R    93.4  0.1 
>>>      
>>>
>>168:03 minimin.x
>>    
>>
>>>26658 f493418   39  19  5396 5396  4188 R N   5.9  0.2   
>>>      
>>>
>>0:42 random_simplex
>>    
>>
>>>26682 f493418   39  19  5124 5124  4188 R N   5.9  0.1   
>>>      
>>>
>>0:42 random_simplex
>>    
>>
>>>
>>>However, on the second machine they are not:
>>>
>>>
>>>
>>>Linux cn065 2.4.18-18.8.0smp #1 SMP Wed Nov 13 23:11:20 EST 
>>>      
>>>
>>2002 i686 i686 i386 GNU/Linux
>>    
>>
>>>
>>> PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME COMMAND
>>>
>>>26881 f459659   25   0  3452 3452  1032 R    55.6  0.1 
>>>      
>>>
>>137:03 minimin.x
>>    
>>
>>>27630 f493418   39  19  5272 5272  4188 R N  50.6  0.2   
>>>      
>>>
>>4:37 random_simplex
>>    
>>
>>>27654 f493418   39  19  5124 5124  4188 R N  50.6  0.1   
>>>      
>>>
>>4:37 random_simplex
>>    
>>
>>>26873 f459659   25   0  3564 3564  1072 R    44.7  0.1 
>>>      
>>>
>>137:19 minimin.x
>>    
>>
>>>
>>>Renicing the processes has not affect.  Restarting the 
>>>      
>>>
>>processes seems to help.  What might be
>>    
>>
>>>causing this?  Are there any know bugs in the SMP schechuler 
>>>      
>>>
>>in 2.4.18 that might cause this? 
>>    
>>
>>The scheduler does not take priority into account when doing SMP
>>balancing.
>>
>>    
>>
>>>Is there a workaround or does a more recent kernel fix this?
>>>
>>>      
>>>
>>Not as far as I know. I'm working on it in 2.6.
>>
>>
>>
>>    
>>
>
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