Hello Andres,
> But further benchmarks sound like a good idea.
I've started running some benchmarks with pgbench, with varying block &
WAL block sizes. I've done a blog post on a small subset of results,
focussing on block size with SSDs and to validate the significance of the
figures found, see for more details:
http://blog.coelho.net/database/2014/08/08/postgresql-page-size-for-SSD/
I've also found an old post by Tomas Vondra who did really extensive
tests, including playing around with file system options:
http://www.fuzzy.cz/en/articles/ssd-benchmark-results-read-write-pgbench/
The cumulated and consistent result of all these tests, including
Hans-Jürgen Schönig short tests, is that reducing page size on SSDs
increases significantly pgbench reported performance, by about 10%.
I've also done some tests with HDDs which are quite disappointing, with
PostgreSQL running in batch mode: a few seconds at 1000 tps followed by a
catch-up phase of 20 seconds at about 0 (zero) tps, and back to a new
cycle. I'm not sure of which parameter to tweak (postgresql configuration,
linux io scheduler, ext4 options or possibly stay away from ext4) to get
something more stable.
--
Fabien.
