Issues with ondemand governor

[Vishwanath Sripathy]

Hi,

I was trying to investigate performance issues that we were seeing
with some usecases like Video playback on OMAP Platforms with ondemand
governor.
As part of this, I found a tool called cpufreq-bench
(http://lwn.net/Articles/339862) which can be used determine the
performance impact of ondemand governor compared to performacne
governor.
When I ran this tool on OMAP3 (ZOOM3) platform using 2.6.36 kernel
with below command, the worstcase ondemand performance is 35% compared
to performance governor.
cpufreq-bench -l 50000 -s 100000 -x 50000 -y 100000 -g ondemand -r 5 -n 5 -v

I tried the same on x86 platforms and there the worstcase performance
is around 88%.
Attached are the cpufreq-bench logs for x86 and omap3.

Questions:
1. Is this is known limitaiton of ondemand governor?
2. How do we support system usecases (like video playback etc) with
ondemand governor if governor is not able to scale the frequencies in
realtime? Are applications expected to play with scaling_min_freq to
increase mpu frequency?

Regards
Vishwa
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