[Beowulf] frequency scaling

[Seth Bardash]

 -----Original Message-----
From: Beowulf [mailto:beowulf-bounces at beowulf.org] On Behalf Of
Christopher Samuel
Sent: Monday, September 21, 2015 5:07 PM
To: beowulf at beowulf.org
Subject: Re: [Beowulf] frequency scaling

On 21/09/15 23:18, Mahmood Sayed wrote:

> Nuke it from the bios. It's the only way to be sure. 

Actually it's not as the kernel intel_idle driver will ignore your
BIOS
or UEFI settings and try and save power anyway..

We use:

intel_idle.max_cstate=0 processor.max_cstate=1

as part of our kernel boot options, originally found here some
time ago:

http://www.mellanox.com/related-docs/prod_software/Mellanox_EN_for
_Linux_User_Manual_v2_0-3_0_0.pdf

Best of luck!
Chris
 -----Original Message-----

Actually we use a different method:

On one machine run 
cpupower frequency-info

analyzing CPU 0:
  driver: acpi-cpufreq
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software:
0
  maximum transition latency: 5.0 us.
  hardware limits: 1.40 GHz - 2.60 GHz
  available frequency steps: 2.60 GHz, 1.40 GHz
  available cpufreq governors: conservative, userspace, powersave,
ondemand, performance
  current policy: frequency should be within 2.60 GHz and 2.60
GHz.
                  The governor "performance" may decide which
speed to use
                  within this range.
  current CPU frequency is 2.60 GHz (asserted by call to
hardware).
  boost state support:
    Supported: yes
    Active: yes
    Boost States: 2
    Total States: 7
    Pstate-Pb0: 3200MHz (boost state)
    Pstate-Pb1: 2900MHz (boost state)
    Pstate-P0:  2600MHz
    Pstate-P1:  2600MHz
    Pstate-P2:  2600MHz
    Pstate-P3:  2600MHz
    Pstate-P4:  1400MHz


The above is the result after using the command:

cpupower frequency-set -d 2600MHz -g performance

The package is cpupowerutils.
You can put this into your start up file like rc.local or a login
file that runs when a user logs in (with su or sudo if needed).

This allows us to use the built-in cpu frequency control (OS and
BIOS) and set the processor to its maximum standard speed while
still making the boost speeds available if they are needed due to
load (limited by temperature or power). You can change the lowest
speed ( -d speed ) to match your power and performance
requirements.

This processor happens to be a single AMD 6212 in a compute node
in an RDO cloud with a standard freq of 2600MHz and a boost speed
of 3200MHz running CentOS 7.1.

YMMV,

Seth Bardash

Integrated Solutions and Systems
1510 Old North Gate Road
Colorado Springs, CO 80921

Failure can not cope with knowledge and perseverance! 

-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2015.0.6140 / Virus Database: 4419/10677 - Release Date:
09/21/15