Re: checkpointer continuous flushing

Hello Tomas,

> I'm planning to do some thorough benchmarking of the patches proposed in this
> thread, on various types of hardware (10k SAS drives and SSDs). But is that
> actually needed? I see Andres did some testing, as he posted summary of the
> results on 11/12, but I don't see any actual results or even info about what
> benchmarks were done (pgbench?).
>
> If yes, do we only want to compare 0001-ckpt-14-andres.patch against master,
> or do we need to test one of the previous Fabien's patches?

My 0.02€,

Although I disagree with some aspects of Andres patch, I'm not a committer
and I'm tired of arguing. I'm just planing to do minor changes to Andres
version to fix a potential issue if the file is closed which flushing is
in progress, but that will not change the overall shape of it.

So testing on Andres version seems relevant to me.

For SSD the performance impact should be limited. For disk it should be
significant if there is no big cache in front of it. There were some
concerns raised for some loads in the thread (shared memory smaller than
needed I think?), if you can include such cases that would be great. My
guess is that it should be not very beneficial in this case because the
writing is mostly done by bgwriter & worker in this case, and these are
still random.

--
Fabien.