Re: Sorted writes in checkpoint

On Thu, 14 Jun 2007, ITAGAKI Takahiro wrote:

> I think we need a discussion board for I/O performance issues. Can I use
> Developers Wiki for this purpose? Since performance graphs and result
> tables are important for the discussion, so it might be better than
> mailing lists, that are text-based.

I started pushing some of my stuff over to there recently to make it
easier to edit and other people can expand with their expertise.
http://developer.postgresql.org/index.php/Buffer_Cache%2C_Checkpoints%2C_and_the_BGW
is what I've done so far on this particular topic.

What I would like to see on the Wiki first are pages devoted to how to run
the common benchmarks people use for useful performance testing. A recent
thread on one of the lists reminded me how easy it is to get worthless
results out of DBT2 if you don't have any guidance on that. I've already
got a stack of documentation about how to wrestle with pgbench and am
generating more.

The problem with using the Wiki as the main focus is that when you get to
the point that you want to upload detailed test results, that interface
really isn't appropriate for it. For example, in the last day I've
collected up data from about 400 short tests runs that generated 800
graphs. It's all organized as HTML so you can drill down into the
specific tests that executed oddly. Heikki's DBT2 resuls are similar; not
as many files, because he's running longer tests, but the navigation is
even more complicated.

There is no way to easily put that type and level of information into the
Wiki page. You really just need a web server to copy the results onto.
Then the main problem you have to be concerned about is a repeat of the
OSDL situation, where all the results just dissapear if their hosting
sponsor goes away.

--
* Greg Smith gsmith(at)gregsmith(dot)com http://www.gregsmith.com Baltimore, MD