Re: Performance tuning on FreeBSD

On Mon, 3 Mar 2008, alan bryan wrote:

>> pgbench -c 100 -t 1000 testdb
> tps = 558.013714 (excluding connections establishing)
>
> Just for testing, I tried turning off fsync and got:
> tps = 4061.662041 (excluding connections establishing)

This is odd.  ~500 is what I expect from this test when there is no write
cache to accelerate fsync, while ~4000 is normal for your class of
hardware when you have such a cache.  Since you say your 3Ware card is
setup with a cache and a BBU, that's suspicious--you should be able to get
around 4000 with fsync on.  Any chance you have the card set to
write-through instead of write-back?  That's the only thing that comes to
mind that would cause this.

--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD