ondemand question?

ondemand question?

[Nebojsa Trpkovic]

Can someone tell me how often "ondemand" governor can switch between CPU 
frequencies (How often does it poll CPU usage and decide what to do?)


Thank you.

RE: ondemand question?

[Pallipadi, Venkatesh]

>-----Original Message-----
>From: cpufreq-bounces@www.linux.org.uk 
>[mailto:cpufreq-bounces@www.linux.org.uk] On Behalf Of Nebojsa Trpkovic
>Sent: Sunday, October 24, 2004 12:11 PM
>To: cpufreq@www.linux.org.uk
>Subject: ondemand question?
>
>Can someone tell me how often "ondemand" governor can switch 
>between CPU 
>frequencies (How often does it poll CPU usage and decide what to do?)
>
>
>Thank you.
>

The frequency is not fixed. Default freq will depend on what amount of
time does CPU actually take to change the frequency. And user can change
this default value within some limits.

Once you start using ondemand governor you will find this (and other
ondemand tunables here)
/sys/devices/..../cpufreq/ondemand/sampling_rate
/sys/devices/..../cpufreq/ondemand/sampling_rate_max
/sys/devices/..../cpufreq/ondemand/sampling_rate_min
(all the numbers here are in uS)

Thanks,
Venki

Re: ondemand question?

[Nebojsa Trpkovic]

Pallipadi, Venkatesh wrote:

>The frequency is not fixed. Default freq will depend on what amount of
>time does CPU actually take to change the frequency. And user can change
>this default value within some limits.
>
>Once you start using ondemand governor you will find this (and other
>ondemand tunables here)
>/sys/devices/..../cpufreq/ondemand/sampling_rate
>/sys/devices/..../cpufreq/ondemand/sampling_rate_max
>/sys/devices/..../cpufreq/ondemand/sampling_rate_min
>(all the numbers here are in uS)
>
>Thanks,
>Venki
>  
>
Thank you. I made changes I needed. Only thing I don't understand here 
is purpose of "sampling_down_factor", but I think I have some idea what 
it can be (because of slow slowing down of the CPU)...

Thank you.

RE: ondemand question?

[Pallipadi, Venkatesh]

 

>-----Original Message-----
>From: cpufreq-bounces@www.linux.org.uk 
>[mailto:cpufreq-bounces@www.linux.org.uk] On Behalf Of Nebojsa Trpkovic
>Sent: Tuesday, October 26, 2004 12:34 AM
>To: cpufreq@www.linux.org.uk
>Subject: Re: ondemand question?
>
>Pallipadi, Venkatesh wrote:
>
>>The frequency is not fixed. Default freq will depend on what amount of
>>time does CPU actually take to change the frequency. And user 
>can change
>>this default value within some limits.
>>
>>Once you start using ondemand governor you will find this (and other
>>ondemand tunables here)
>>/sys/devices/..../cpufreq/ondemand/sampling_rate
>>/sys/devices/..../cpufreq/ondemand/sampling_rate_max
>>/sys/devices/..../cpufreq/ondemand/sampling_rate_min
>>(all the numbers here are in uS)
>>
>>Thanks,
>>Venki
>>  
>>
>Thank you. I made changes I needed. Only thing I don't understand here 
>is purpose of "sampling_down_factor", but I think I have some 
>idea what 
>it can be (because of slow slowing down of the CPU)...
>
>Thank you.
>

sampling_down_factor - When it is 1, ondemand checks for frequency 
increase and decrease at the same period/frequency. When it is n, 
ondemand checks for frequency decrease once after n checks 
for frequency increase.

Thanks,
Venki

Re: ondemand question?

[Nebojsa Trpkovic]

Pallipadi, Venkatesh wrote:

> 
>sampling_down_factor - When it is 1, ondemand checks for frequency 
>increase and decrease at the same period/frequency. When it is n, 
>ondemand checks for frequency decrease once after n checks 
>for frequency increase.
>
>Thanks,
>Venki
>  
>
Exactly what I thought. Great!

Thank you very much!