| From: | "Guillaume Smet" <guillaume(dot)smet(at)gmail(dot)com> |
|---|---|
| To: | "Simon Riggs" <simon(at)2ndquadrant(dot)com> |
| Cc: | pgsql-performance <pgsql-performance(at)postgresql(dot)org>, "Stefan Kaltenbrunner" <stefan(at)kaltenbrunner(dot)cc> |
| Subject: | Re: More shared buffers causes lower performances |
| Date: | 2007-12-26 15:41:24 |
| Message-ID: | 1d4e0c10712260741w1f141fd6x2f482143d526ad48@mail.gmail.com |
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| Lists: | pgsql-performance |
On Dec 26, 2007 12:21 PM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> bgwriter_lru_maxpages = 0
>
> So we can see if the bgwriter has any hand in this?
It doesn't change the behaviour I have.
It's not checkpointing either as using pgbench-tools, I can see that
tps and latency are quite stable during the entire run. Btw, thanks
Greg for these nice tools.
I thought it may be some sort of lock contention so I made a few tests
with -N but I have the same behaviour.
Then I decided to perform read-only tests using -S option (pgbench -S
-s 100 -c 16 -t 30000 -U postgres bench). And still the same
behaviour:
shared_buffers=64MB : 20k tps
shared_buffers=1024MB : 8k tps
Any other idea?
--
Guillaume
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