Re: Linux 2.4.18 Scheduler Bug?

[Nick Piggin]

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@xxxxxxxxxxxxxxx]
> > 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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