[sles-beta] intel_idle

[Waite, Dick]

Many Thanks for the update Scott. A couple / few of customers did not like the idea of having to amend the boot parm and at the time some words were written about using in a later kernel, syscntl.conf which customers preferred over amending boot as their system providers charged extra...

If the parm was not in boot then I think more customers would be willing to amend this value, I wonder how many customer get better results with the default, do you have any numbers?

__R
________________________________________
From: Scott Bahling [sbahling at suse.com]
Sent: 23 July 2014 12:09
To: Waite, Dick
Cc: sles-beta at lists.suse.com
Subject: Re: [sles-beta] intel_idle

On Wed, 2014-07-23 at 06:55 +0000, Waite, Dick wrote:
> Grand Day,
>
>     When running some SLES11 on X86_64 sites some time ago the "batch"
> jobs were taking 30-50% more wall clock time. After some time a
> work-a-round was found to amend the "Intel_Idle" parm. There was some
> chatter at the time that a "better" fix would be available with a
> later Linux release. I'm going to visit one of our customers who had
> this issue in a few weeks time, what news do I have for them?

It depends on the exact tuning ("work-a-round") used.

There has been an optimization related to disabling promotion to C1E
state so using intel_idle.max_cstate=1 might give better results with
SUSE Linux Enterprise Server 12 and remove the need to disable the
intel_idle driver completely. It depends on the workload and CPU model
in use.

Other than that, the intel_idle driver and it's parameters should work
the same in 12 as in 11 - meaning if c-states affect your workload,
tuning of the intel_idle driver might be necessary.

Best Regards,

Scott

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