Re: AIX pinned memory

  • From: Mladen Gogala <mgogala@xxxxxxxxxxx>
  • To: Brandon.Allen@xxxxxxxxxxx
  • Date: Thu, 14 Dec 2006 21:10:41 -0500

On 12/14/2006 05:46:19 PM, Allen, Brandon wrote:

> And I'm not sure, but the vmstat man page leads me to believe that this
> pool may include FS buffers,

This may be the key: if buffer pages are dynamically pinned an 
not set to DIRECTIO or SETALL, then the difference you're seeing might be 
explained by
AIX file system buffers used to cache database files. I assume that your 
database is 
on JFS2, which supports not only direct and asynchronous I/O but also something 
"concurrent I/O" which additionally speeds up I/O from shared memory segments.
Actionable advice: set your FILESYSTEMIO_OPTIONS parameter to SETALL (there is 
no reason
not to do so on AIX) and see whether the number of pinned pages has decreased.

Mladen Gogala


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