Re: [PERFORM] Swapping on Solaris

[Kevin Schroeder]

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" <[EMAIL PROTECTED]>
To: "Kevin Schroeder" <[EMAIL PROTECTED]>
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


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