Optimizing CPU Frequency on OpenPOWER distributions

Before we go on to look at optimizing the CPU frequency on Power systems, it is important to know what frequency you are running at. For this make sure you have powerpc-utils package installed.

On Fedora 

dnf install powerpc-utils

On CentOS

yum install powerpc-utils

On Ubuntu:

apt-get install powerpc-utils

Once you install this package, you can run the following command to know the frequency your CPU can run at:

sudo ppc64_cpu  --frequency

STEP 1 of Optimization:

To optimize CPU frequency for OpenPOWER distributions for ppc64le we first need install the kernel module specific to POWER-PC Architecture and then change the governor to “performance” enhancing mode.

On Fedora and some other openPOWER distributions this kernel module is not installed by default. For example: On Barreleye server, because of absence of this module on Fedora 23, Kernel doesn’t have enough info to scale the CPU very well. And hence puts CPU at a defensive “2.0 Ghz” instead of full “3.5 Ghz”.

Here is how you load the kernel module specific to PPC64LE to make sure CPU scales.

sudo modprobe powernv-cpufreq

STEP 2:

Next step is to Change the governor to the one that gives you best performance . Here is the list of default governors for different OS and what it can to be changed to for best performance. Please note the performance governor may not necessarily be needed for your workload, but is good to to have for getting best performance out of the system.

OS / Distribution	DEFAULT CPU Frequency scaling Governor on PPC	BEST CPU governor for  performance on PPC	Linux Package needed to set governer	Linux command for setting governor to performance
Fedora	None (since builds are missing kernel module for frequency scaling)	performance	cpufrequtils	cpufreq-set -g performance
CentOS	conservative	performance	cpufrequtils	cpupower frequency-set -g performance
Ubuntu	ondemand	performance	cpufrequtils	cpupower frequency-set -g performance

 

In my specific example, once we load this module on Fedora, and set the governor to “performance” Barreleye  (openPOWER server) starts to run at the full frequency.

Before loading the module:

[root@localhost ~]# sudo ppc64_cpu  –frequency
min:    2.063 GHz (cpu 126)
max:    2.063 GHz (cpu 0)
avg:    2.063 GHz

 After loading the module:

[live@localhost ~]$ sudo ppc64_cpu  –frequency

min:    3.494 GHz (cpu 120)
max:    3.494 GHz (cpu 7)
avg:    3.494 GHz

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How to set openBMC to use static address

Good number of openPOWER servers run openBMC. OpenBMC as of today does NOT support network IPMI but it does support host-BMC IPMI. We can use this to set static IP on BMC using standard IPMI tool commands

Set openBMC to static IP from Host / Petitboot:

To set the BMC running openBMC to static address, run following ipmitool commands from petitboot / host.

   ipmitool lan set 1 ipsrc static

   ipmitool lan set 1 ipaddr 10.127.xx.xx

   ipmitool lan set 1 netmask 255.255.252.0

   ipmitool lan set 1 defgw ipaddr 10.127.xx.xx

   ipmitool raw 0x06 0x40

You can print lan credentials using:

ipmitool lan print

Remember default credentials of BMC is    root   and 0penBmc

Set openBMC to get static IP from openBMC linux shell:

You can use standard linux “ip” command to set the IP address to static

To check interfaces

ip a

To force eth0 down

ip link set eth0 down

To force eth0 up

ip link set eth0 up

To set static ip

ip addr add 192.168.1.1 dev eth0

To set up routing:

ip route add 192.168.1.0/24 via 192.168.1.1 dev eth0

How to set OpenPOWER server to boot from any device

OpenPOWER servers have Petitboot bootloader to manage the bootup options / preferences.

Since petitboot is relatively new I am putting together this guide to help walk through on how to set up devices to boot from any device (network or disk).

Step 1. 

Power on the server and wait for Petitboot to come up via the VGA console (or OOB)

Step 2:

Select and click “system configuration” using the key-board arrows and enter key.

Setup 3:

You will find below menu to customize the boot up options. In order to boot from any device, select and press enter on ” Clear and boot Any” option as below

Setup 4:

Once you finish step 3, you will see that Boot Order in the first line of the screen short below changes to “(0) Any Device”

Step 5:

Now let’s save this boot config. For saving the boot order we have to go all the way down to the boot menu with down arrow key and select and press enter on “OK”

Step 6:

At this point you will be returned to petitboot menu and you have successfully set to boot from any device. From your next power on your server will automatically boot into an image that it finds first.

Power-off, Unrack and rack your server (or hard reboot) to test that “boot from any device” preference is working. When you un-rack and re-rack your server, you will have to wait few minutes (for BMC orange light to go off) before you press the host power on button.