Re: Memory Usage and OpenBSD

Greg Smith wrote:
> Jeff Ross wrote:
>> I think I'm doing it right.  Here's the whole script.  I run it from
>> another server on the lan.
>
> That looks basically sane--your description was wrong, not your
> program, which is always better than the other way around.
>
> Note that everything your script is doing and way more is done quite
> easily with pgbench-tools:
> http://git.postgresql.org/gitweb?p=pgbench-tools.git;a=summary
>
> You can just dump a list of scales and client counts you want to test
> and let that loose, it will generate graphs showing TPS vs.
> scale/clients and everything if gnuplot is available.
>

Cool!  I'll get gnuplot installed and have some runs going before long.

>> transaction type: TPC-B (sort of)
>> scaling factor: 70
>> query mode: simple
>> number of clients: 70
>> number of transactions per client: 20000
>> number of transactions actually processed: 1400000/1400000
>> tps = 293.081245 (including connections establishing)
>> tps = 293.124705 (excluding connections establishing)
>
> This is way more clients than your server is going to handle well on
> pgbench's TPC-B test, which is primarily a test of hard disk write
> speed but it will get bogged down with client contention in many
> conditions.  Performance degrades considerably as the number of
> clients increases much past the number of cores in the server;
> typically 1.5 to 2X as many clients as cores gives peak throughput.
>
> I'm not sure what's causing your panic--not enough BSD practice.  But
> I think Tom's suggestion of vastly decreasing from:
>
> maintenance_work_mem = 240MB
>
> Is worth trying.  Reducing it won't hurt pgbench performance on quick
> tests, just how long it takes to get the tests setup.
>

Okay, I'll try that.  Hopefully if I can get it to run well under
pgbench the same setup will work well with drupal.  The site I was
worried about when I went to this bigger server has started a little
slower than originally projected so the old server is handling the load.

> Sorry about pgtune being a bit aggressive in what it suggests--on the
> TODO list to scale it back, and hopefully provide more helpful
> suggestions for kernel tuning too.
>
One of my goals (once I get all this figured out) is to provide some
guide lines on how to best configure OpenBSD to run PostgreSQL.

Thanks for all of your work and tools, Greg!

> --  Greg Smith    2ndQuadrant   Baltimore, MD
> PostgreSQL Training, Services and Support
> greg@2ndQuadrant.com  www.2ndQuadrant.com
>

Jeff Ross