Re: pgtune + configurations with 9.3

I have done some tests using pgbench-tools with different configurations on
our new server with 768G RAM and it seems for our purpose 32G
shared_buffers would give the best results.

Regards
Johann

On 17 November 2014 at 07:17, Stuart Bishop <stuart(at)stuartbishop(dot)net> wrote:

> On 15 November 2014 06:00, Mark Kirkwood <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz>
> wrote:
>
> > It is probably time to revisit this 8GB limit with some benchmarking. We
> > don't really have a hard and fast rule that is known to be correct, and
> that
> > makes Alexey's job really difficult. Informally folk (including myself at
> > times) have suggested:
> >
> > min(ram/4, 8GB)
> >
> > as the 'rule of thumb' for setting shared_buffers. However I was recently
>
> It would be nice to have more benchmarking and improve the rule of
> thumb. I do, however, believe this is orthogonal to fixing pgtune
> which I think should be using the current rule of thumb (which is
> overwhelmingly min(ram/4, 8GB) as you suggest).
>
>
>
> > benchmarking a machine with a lot of ram (1TB) and entirely SSD storage
> [1],
> > and that seemed quite happy with 50GB of shared buffers (better
> performance
> > than with 8GB). Now shared_buffers was not the variable we were
> > concentrating on so I didn't get too carried away and try much bigger
> than
> > about 100GB - but this seems like a good thing to come out with some
> numbers
> > for i.e pgbench read write and read only tps vs shared_buffers 1 -> 100
> GB
> > in size.
>
> I've always thought the shared_buffers setting would need to factor in
> things like CPU speed and memory access, since the rational for the
> 8GB cap has always been the cost to scan the data structures. And the
> kernel would factor in too, since the PG specific algorithms are in
> competition with the generic OS algorithms. And size of the hot set,
> since this gets pinned in shared_buffers. Urgh, so many variables.
>
> --
> Stuart Bishop <stuart(at)stuartbishop(dot)net>
> http://www.stuartbishop.net/
>
>
> --
> Sent via pgsql-performance mailing list (pgsql-performance(at)postgresql(dot)org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-performance
>

--
Because experiencing your loyal love is better than life itself,
my lips will praise you. (Psalm 63:3)