| From: | Csaba Nagy <nagy(at)ecircle-ag(dot)com> |
|---|---|
| To: | Heikki Linnakangas <heikki(at)enterprisedb(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 11:34:22 |
| Message-ID: | 1190374462.4661.199.camel@PCD12478 |
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| Lists: | pgsql-performance |
On Fri, 2007-09-21 at 11:34 +0100, Heikki Linnakangas wrote:
> Which version of Postgres is this? In 8.3, a scan like that really won't
> suck it all into the shared buffer cache. For seq scans on tables larger
> than shared_buffers/4, it switches to the bulk read strategy, using only
> a few buffers, and choosing the starting point with the scan
> synchronization facility.
>
This was on 8.1.9 installed via apt-get on Debian 4.1.1-21. In any case
I'm pretty sure linux swaps shared buffers, as I always got worse
performance for shared buffers more than about 1/3 of the memory. But in
that case the output of top is misleading.
Cheers,
Csaba.
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