Re: Some performance testing?

Hey Mike,

What those graphs are showing is that the new kernel reduces the IO required for the same DB load. At least, that’s how we’re supposed to interpret it.

I’d be curious to see a measure of the database load for both of those so we can verify that the new kernel does in fact provide better performance.

-Wes

From: pgsql-performance-owner(at)postgresql(dot)org [mailto:pgsql-performance-owner(at)postgresql(dot)org] On Behalf Of Michael Nolan
Sent: Wednesday, April 08, 2015 5:09 PM
To: Josh Berkus
Cc: Mel Llaguno; Przemysław Deć; pgsql-performance(at)postgresql(dot)org
Subject: Re: [PERFORM] Some performance testing?

On Wed, Apr 8, 2015 at 3:05 PM, Josh Berkus <josh(at)agliodbs(dot)com<mailto:josh(at)agliodbs(dot)com>> wrote:
On 04/07/2015 11:07 AM, Mel Llaguno wrote:
> Care to elaborate? We usually do not recommend specific kernel versions
> for our customers (who run on a variety of distributions). Thanks, M.

You should.

http://www.databasesoup.com/2014/09/why-you-need-to-avoid-linux-kernel-32.html

Performance is literally 2X to 5X different between kernels.

Josh, there seems to be an inconsistency in your blog. You say 3.10.X is safe, but the graph you show with the poor performance seems to be from 3.13.X which as I understand it is a later kernel. Can you clarify which 3.X kernels are good to use and which are not?
--
Mike Nolan