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Re: Memory question

From: "Patrick Hatcher" <PHatcher(at)macys(dot)com>
To: josh(at)agliodbs(dot)com
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Memory question
Date: 2003-06-27 19:58:22
Message-ID: OF52DB8C06.78DFD2FC-ON88256D52.006D26E1-88256D52.006E391A@fds.com (view raw or flat)
Thread:
Lists: pgsql-performance
Shared buffer is now set to 20,000 as suggested.  So far so good.
As far as shmmax, it really is my ignorance of Linux.  We are going to play
around with this number.  Is there a suggested amount since I have
my effective_cache_size = 625000 (or does one have nothing to do with the
other)
Thanks again

Patrick Hatcher




                                                                                                                                       
                    Josh Berkus                                                                                                        
                    <josh(at)agliodbs       To:     "Patrick Hatcher" <PHatcher(at)macys(dot)com>, pgsql-performance(at)postgresql(dot)org              
                    .com>                cc:                                                                                           
                                         Subject:     Re: [PERFORM] Memory question                                                    
                    06/27/2003                                                                                                         
                    12:54 PM                                                                                                           
                    Please respond                                                                                                     
                    to josh                                                                                                            
                                                                                                                                       




Patrick,

> Sorry for posting an obvious Linux question, but have any of you
> encountered this and how have you fixed it.
> I have 6gig Ram box.  I've set my shmmax  to 3072000000.  The database
> starts up fine without any issues.  As soon as a query is ran
> or a FTP process to the server  is done, the used memory shoots up and
> appears to never be released.

What's you shared_buffers set to after our talk?  Do you actually need 3gb
of
shmmax?

> My fear is that this may cause problems for my database if this number
> continues to grow.  Below is my TOP after running a query, and shutting
> down PgAdmin.  While not low now, the amount of free memory has dropped
to
> around 11mg.  I'll admit I'm not that Linux savvy, but am I reading this
> correct?

No.

> Mem:  6711564K av, 6517776K used,  193788K free,       0K shrd,   25168K

The "used" figure in Top doesn't really tell you anything, since it
includes
the kernel buffer which tries to take up all available memory.  If you
actually look at the list of processes, I think you'll find that you're
only
using 1-2% of memory for applications.

I'm not sure what app would show your "real" free memory.

--
-Josh Berkus
 Aglio Database Solutions
 San Francisco





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