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Re: 19990601: Linux LDM memory problem (fwd)

On Thu, 3 Jun 1999, David Wojtowicz wrote:

> 
> 
> Robb,
> 
>  Would it be possible to insert a call to msync (perhaps
> with MS_ASYNC set) after each queue entry modification
> so that writes are scheduled as changes are made?  I'd
> be happy to experiment, but I wasn't sure where such a
> call should be inserted in the code.

David,

After some discussions, we don't think adding msync calls will help the
situation.  It's seems Linux doesn't use the disk part of the queue until
the LDM is terminated.  This is our speculation, the LDM memmap queue is
using the swap space.  What is the size of the swap space on the machine?
If one increases the swap size, does this help the problem?  

This is the configuration of our Linux machine.

Mem:  517556K av, 480364K used,  37192K free, 103992K shrd, 109724K buff
Swap: 642420K av,      0K used, 642420K free                 60252K cached

There isn't an LDM running.  

Let me know the results,
Robb... 



> 
>  I noticed msync is called in pq.c if USE_MSYNC is defined
> but that appears to only be called when closing out the queue.
> Defining it had no useful effect.
> 
> --------------------------------------------------------
>  David Wojtowicz, Research Programmer/Systems Manager
>  Department of Atmospheric Sciences Computer Services
>  University of Illinois at Urbana-Champaign
>  email: address@hidden  phone: (217)333-8390
> --------------------------------------------------------
> 
> 
> 
> 

===============================================================================
Robb Kambic                                Unidata Program Center
Software Engineer III                      Univ. Corp for Atmospheric Research
address@hidden             WWW: http://www.unidata.ucar.edu/
===============================================================================