From: Alan Hodgson <ahodgson@simkin.ca>
To: pgsql-performance@postgresql.org
Subject: Re: Two Necessary Kernel Tweaks for Linux Systems
Date: Tue, 08 Jan 2013 15:24:33 -0800
Message-ID: <1379852.5YF1lC0NFs@skynet.simkin.ca>
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On Tuesday, January 08, 2013 03:48:38 PM Shaun Thomas wrote:
> On 01/08/2013 02:05 PM, AJ Weber wrote:
> > Is there an "easy" way to tell what scheduler my OS is using?
> 
> Unfortunately not. I looked again, and it seems that CFS was merged into
> 2.6.23. Anything before that is probably safe, but the vendor may have
> backported it. If you don't see the settings I described, you probably
> don't have it.
> 
> So I guess Midge had 2.6.18, which predates the merge in 2.6.23.
> 
> I honestly don't understand the Linux kernel sometimes. A process
> scheduler swap is a *gigantic* functional change, and it's in a dot
> release. I vastly prefer PostgreSQL's approach...

Red Hat also selectively backports major functionality into their enterprise 
kernels. If you're running RHEL or a clone like CentOS, the reported kernel 
version has little bearing on what may nor may not be in your kernel.

They're very well tested and stable, so there's nothing wrong with them, per 
se, but you can't just say oh, you have version xxx, you don't have this 
functionality.


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