Re: PostgreSQL performance on various distribution stock kernels

On Nov 26, 2007 4:50 PM, Damon Hart  wrote:
>
> So, what's different between these tests? I'm seeing performance
> differences of between +65% to +90% transactions per second of the
> OpenVZ kernel running on the HN over the stock Fedora 8 kernel. Is
> this reflective of different emphasis between RHEL and Fedora kernel
> builds?  Some OpenVZ optimization on top of the RHEL5 build? Something
> else? Where should I look?
>
> any insights much appreciated,

How many TPS are you seeing on each one?  If you are running 10krpm
drives and seeing more than 166.66 transactions per second, then your
drives are likely lying to you and not actually fsyncing, and it could
be that fsync() on IDE / SATA has been implemented in later kernels
and it isn't lying.

Hard to say for sure.

What does vmstat 1 have to say on each system when it's under load?