Cannot disable frequency scaling on Arndale-Ubuntu

[sumanth]

 I set the CPU0 in performance mode and set frequency to 1.7GHz before starting the benchmark. After the benchmark runs, I find that the scaling governor is still performance but frequency was scaled down to 800MHz. Looking at the numbers, this seems to have happened almost immediately after starting the benchmark.
 I looked at running process and daemons and couldn’t find anything similar to thermald or dvsc (these are in Android).
Also, turning off CPU1 causes the system to panic and crash

[Marcin Juszkiewicz (hrw)]

And that's on Efika MX Smartbook or R/Pi?

</sarcasm>

[sumanth (sgundapa)]

This is on arndale board with ubuntu image 13.02

[Tushar Behera (tusharbehera)]

I tested with the linux-linaro kernel (ll-20130412.0), but couldn't reproduce the problem.

I changed the governor to 'performance' and checked the value of '/sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq' every second for 10 minutes. The value was 1700MHz every time.

[sumanth (sgundapa)]

I tried to run my benchmark on Linaro 13.02 ubuntu image. Can you try running a pay load which may trigger the change ? I have no idea on where to get the image which you were trying

[sumanth (sgundapa)]

The benchmark which I am running is SPEC2006 which is CPU intensive

[Fathi Boudra (fboudra)]

On 16 April 2013 19:52, sumanth <email address hidden> wrote:
> I tried to run my benchmark on Linaro 13.02 ubuntu image. Can you try
> running a pay load which may trigger the change ? I have no idea on
> where to get the image which you were trying

upgrade your kernel:
apt-get update
apt-get dist-upgrade

You should get the same kernel used by Tushar.

[sumanth (sgundapa)]

I will upgrade and will let you know the status

-----Original Message-----
From: <email address hidden> [mailto:<email address hidden>] On Behalf Of Fathi Boudra
Sent: Tuesday, April 16, 2013 10:06 AM
To: Gundapaneni, Sumanth
Subject: Re: [Bug 1169257] Re: Cannot disable frequency scaling on Arndale-Ubuntu

On 16 April 2013 19:52, sumanth <email address hidden> wrote:
> I tried to run my benchmark on Linaro 13.02 ubuntu image. Can you try
> running a pay load which may trigger the change ? I have no idea on
> where to get the image which you were trying

upgrade your kernel:
apt-get update
apt-get dist-upgrade

You should get the same kernel used by Tushar.

--
You received this bug notification because you are subscribed to the bug report.
https://bugs.launchpad.net/bugs/1169257

Title:
  Cannot disable frequency scaling on Arndale-Ubuntu

Status in Arndale Support:
  New
Status in Linaro Samsung Landing Team Project:
  Incomplete

Bug description:
   I set the CPU0 in performance mode and set frequency to 1.7GHz before starting the benchmark. After the benchmark runs, I find that the scaling governor is still performance but frequency was scaled down to 800MHz. Looking at the numbers, this seems to have happened almost immediately after starting the benchmark.
   I looked at running process and daemons and couldn’t find anything similar to thermald or dvsc (these are in Android).
  Also, turning off CPU1 causes the system to panic and crash

To manage notifications about this bug go to:
https://bugs.launchpad.net/arndale/+bug/1169257/+subscriptions

[sumanth (sgundapa)]

I will upgrade and let you know the status

[sumanth (sgundapa)]

I upgraded and ran my benchmark. The problem still persists.
You could probably try at your end loading the CPU and can verify this behavior. Gzip can be CPU intensive.

[sumanth (sgundapa)]

Also, I would like to know of any deamon which maintains the temperature of CPU ?

[Tushar Behera (tusharbehera)]

AFAIK, there is no daemon that maintains the temperature of CPU, but you can get the current temperature by reading the sysfs entry.

/sys/devices/virtual/thermal/thermal_zone0/temp

I am running gzip and checking the time spent in various freq. through following sysfs entry.

cat /sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state

It shows that I am spending time in 1700MHz always when I set performance governor.

Can you please provide us the complete boot log?

[sumanth (sgundapa)]

I have attached the boot log which you asked. I got this using dmesg

[Tushar Behera (tusharbehera)]

Boot log suggests that you are running 3.8 kernel. Please try with latest kernel.

[sumanth (sgundapa)]

Could you be more specific how I can update my kernel ? Any pre-built image ?

[sumanth (sgundapa)]

Never mind. I updated to kernel version 3.9 and I will update you the status on this one.

[sumanth (sgundapa)]

This one worked. But I do see other problems.

1. The frequencies and stats of cpu1 are the same as of cpu0.
why is it mirroring the values from cpu0 ?

2. Setting the cpu1 to offline crashes the system.
$ echo 0 > /sys/devices/system/cpu/cpu1/online

These settings are important for my experiments to measure the performance.

Let me know if you need more information.

[Tushar Behera (tusharbehera)]

> 1. The frequencies and stats of cpu1 are the same as of cpu0.
> why is it mirroring the values from cpu0 ?
>

AFAIK, both the CPUs run at same frequency. Hence the mirroring.

> 2. Setting the cpu1 to offline crashes the system.
> $ echo 0 > /sys/devices/system/cpu/cpu1/online
>

This is a known bug and we are working on fixing this.

https://bugs.launchpad.net/linaro-landing-team-samsung/+bug/1128729

--
Tushar Behera

[Fathi Boudra (fboudra)]

Closing this bug since latest kernel works wrt disabling frequency scaling.
Please, follow up on bug #1128729 for the other known issue.