korakios
Posts: 7
Joined: Sun Jan 25, 2015 12:39 pm

How "initial_turbo" works?

Fri Jun 05, 2015 4:14 pm

Hi,
I can't understand how "initial_turbo" works. I've set my Raspberry running at 800Hz but would like to go up to 1000Hz only while booting (for speed). Is initial_turbo mode suitable? Do I have to make other adjustments?
Thanks!

JimmyN
Posts: 1109
Joined: Wed Mar 18, 2015 7:05 pm
Location: Virginia, USA

Re: How "initial_turbo" works?

Fri Jun 05, 2015 7:33 pm

It sets turbo mode from start of boot until the point when cpufreq sets the frequency, or you can specify a number of seconds. You could turn off the speed governor and use initial_turbo and you'd only have turbo during the boot. But I don't think you're going to see much of a performance difference because at that point the SD cards read speed is probably more of a limiting factor than the clock frequency. IMO bumping the clock rates up and down during the initial boot process when it's setting everything up could be an exercise fraught with peril, and would likely only make a few seconds difference in boot time anyway.

korakios
Posts: 7
Joined: Sun Jan 25, 2015 12:39 pm

Re: How "initial_turbo" works?

Sat Jun 06, 2015 10:14 am

Thanks JimmyN ,
I was wondering if turbo worked as I didn't noticed any big improvement on booting. Maybe I'll try a fast sad card first.

JimmyN
Posts: 1109
Joined: Wed Mar 18, 2015 7:05 pm
Location: Virginia, USA

Re: How "initial_turbo" works?

Sat Jun 06, 2015 2:03 pm

During the boot the random read speed for smaller files is the most important value. So a class 4 or 6 may actually boot faster than a class 10 which works best for larger file sequential reads. And the speed will vary according to the SD manufacturer and the controller they're using on the card. If you're looking for the fastest boot speeds you may want to search a little for SD benchmarks and pick one that is fastest for random seek/read operations.

Return to “Beginners”