Re: Why we are going to have to go DirectIO

On 12/05/2013 05:48 AM, Stephen Frost wrote:
> * Peter Geoghegan (pg(at)heroku(dot)com) wrote:
>> On Wed, Dec 4, 2013 at 11:07 AM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
>>> But you know what? 2.6, overall, still performs better than any kernel
>>> in the 3.X series, at least for Postgres.
>>
>> What about the fseek() scalability issue?
>
> Not to mention that the 2.6 which I suspect you're referring to (RHEL)
> isn't exactly "2.6"..

Actually, I've been able to do 35K TPS on commodity hardware on Ubuntu
10.04. I have yet to go about 15K on any Ubuntu running a 3.X Kernel.
The CPU scheduling on 2.6 just seems to be far better tuned, aside from
the IO issues; at 35K TPS, the CPU workload is evenly distributed across
cores, whereas on 3.X it lurches from core to core like a drunk in a
cathedral. However, the hardware is not identical, and this is on
proprietary, not benchmark, workloads, which is why I haven't published
anything.

--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com