Re: Swapping on Solaris

I may be asking the question the wrong way, but when I start up PostgreSQL
swap is what gets used the most of.  I've got 1282MB free RAM right now and
and 515MB swap in use.  Granted, swap file usage probably wouldn't be zero,
but I would guess that it should be a lot lower so something must be keeping
PostgreSQL from using the free RAM that my system is reporting.  For
example, one of my postgres processes is 201M in size but on 72M is resident
in RAM.  That extra 130M is available in RAM, according to top, but postgres
isn't using it.

Kevin

----- Original Message -----
From: "Alan Stange" <stange@rentec.com>
To: "Kevin Schroeder" <kschroeder@mirageworks.com>
Cc: <pgsql-performance@postgresql.org>
Sent: Wednesday, January 19, 2005 9:30 AM
Subject: Re: [PERFORM] Swapping on Solaris


> Kevin Schroeder wrote:
>
>> I suspect that the memory is being used to cache files as well since the
>> email boxes are using unix mailboxes, for the time being.  With people
>> checking their email sometimes once per minute I can see why Solaris
>> would want to cache those files.  Perhaps my question would be more
>> appropriate to a Solaris mailing list since what I really want to do is
>> get Solaris to simply allow PostgreSQL to use more RAM and reduce the
>> amount of RAM used for file caching.  I would have thought that Solaris
>> gives some deference to a running application that's being swapped than
>> for a file cache.
>>
>> Is there any way to set custom parameters on Solaris' file-caching
>> behavior to allow PostgreSQL to use more physical RAM?
>
> Your explanation doesn't sound quite correct.   If postgresql malloc()'s
> some memory and uses it, the file cache will be reduced in size and the
> memory given to postgresql.   But if postgresql doesn't ask for or use the
> memory, then solaris is going to use it for something else.  There's
> nothing in Solaris that doesn't "allow" postgresql to use more RAM.
>
> -- Alan
>
>
>