Used Memory Not Clearing Down On Redhat Machines.

[Smith, Albert]

> -----Original Message-----
> From: redhat-list-bounces at redhat.com 
> [mailto:redhat-list-bounces at redhat.com] On Behalf Of Eris Caffee
> Sent: Friday, August 12, 2005 11:17 AM
> To: General Red Hat Linux discussion list
> Subject: Re: Used Memory Not Clearing Down On Redhat Machines.
> 
> > 15:20:33  up 14 days,  2:16,  1 user,  load average: 0.00, 
> 0.00, 0.00
> > 49 processes: 48 sleeping, 1 running, 0 zombie, 0 stopped
> > CPU states:  cpu    user    nice  system    irq  softirq  
> iowait    idle
> >            total    0.8%    0.0%    0.2%   0.0%     0.6%    
> 0.0%  198.4%
> >            cpu00    0.0%    0.0%    0.0%   0.0%     0.0%    
> 0.0%  100.0%
> >            cpu01    0.8%    0.0%    0.2%   0.0%     0.6%    
> 0.0%   98.4%
> > Mem:  3599032k av, 2926964k used,  672068k free,       0k 
> shrd,   82052k
> > buff
> >                     469844k actv, 1731916k in_d,   54940k in_c
> > Swap: 2044072k av,       0k used, 2044072k free             
>     2614264k
> > cached
> 
> You have an awful lot of memory in the in_d state.  That is 
> "Inactive Dirty".  There's a description of it and the other 
> memory states (for 2.4 kernels at least) here:
> http://www.redhat.com/magazine/001nov04/features/vm/
> Pages in the inactive dirty state ought to be getting flushed 
> out to disk, but it looks like this isn't happening.
> 
> I'm no kernel expert, but it seems to me that something is 
> causing the kernel not to properly launder the inactive dirty 
> memory.  This could be a kernel bug, so if you are sure you 
> don't have any hung processes that could be holding the 
> memory open, you should check to see if there is a newer 
> kernel available for your system.
> 
> Of course, you should also double check to make sure there 
> really isn't some process from the analysis job still running 
> and holding all of this memory open.
> 
> Eris Caffee
> 
> 
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> 

I did some investigation with RH EL4 and it looks like this memory
problem is addressed with 2.6.x line of kernel. I am currently compiling
2.6.13 manually on my EL3 to see the results.

I will keep you posted.

Albert Smith
Sr. Unix Systems Administrator
HPCSA, RHCT  
Genex Services
440 E. Swedesford Rd.
Wayne, PA 19087
albert.smith at genexservices.com
(610) 964-5154