| From: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
|---|---|
| To: | Csaba Nagy <nagy(at)ecircle-ag(dot)com> |
| Cc: | Gregory Stark <stark(at)enterprisedb(dot)com>, Decibel! <decibel(at)decibel(dot)org>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Linux mis-reporting memory |
| Date: | 2007-09-21 11:01:18 |
| Message-ID: | 1190372478.4202.17.camel@ebony.site |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
On Fri, 2007-09-21 at 12:08 +0200, Csaba Nagy wrote:
> On Fri, 2007-09-21 at 10:43 +0100, Gregory Stark wrote:
> > The other possibility is that Postgres just hasn't even touched a large part
> > of its shared buffers.
> >
>
> But then how do you explain the example I gave, with a 5.5GB table
> seq-scanned 3 times, shared buffers set to 12 GB, and top still showing
> almost 100% memory as cached and no SWAP "used" ? In this case you can't
> say postgres didn't touch it's shared buffers - or a sequential scan
> won't use the shared buffers ?
Well, 6.5GB of shared_buffers could be swapped out and need not be
swapped back in to perform those 3 queries.
--
Simon Riggs
2ndQuadrant http://www.2ndQuadrant.com
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Csaba Nagy | 2007-09-21 11:29:26 | Re: Searching for the cause of a bad plan |
| Previous Message | Simon Riggs | 2007-09-21 10:59:25 | Re: Searching for the cause of a bad plan |