Re: More shared buffers causes lower performances

On Dec 26, 2007 12:21 PM, Simon Riggs <simon@2ndquadrant.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