Re: poor performance of OpenEmbedded on, BeagleBoneBlack compared to Debian

["Peter A. Bigot" <pab@pabigot.com>]

On 09/04/2014 10:00 AM, Denys Dmytriyenko wrote:
> On Thu, Sep 04, 2014 at 02:50:03PM +0000, Mikhail Zakharov wrote:
>> On Wed, Sep 3, 2014 at 8:59 PM, Peter A. Bigot <pab@pabigot.com> wrote:
>>
>>> One anomaly I've found is the CPU frequency range.  On debian we have:
>>>
>>>     debian@beaglebone:~$ cat
>>> /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
>>>     300000 600000 800000 1000000
>>>
>>> while on OE we have:
>>>
>>>     root@beaglebone:~# cat
>>> /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
>>>     300000 600000 720000 800000
>> Stock yocto-bsp is missing a few things that can be found in Robert
>> Nelson's patchset for 3.14 linux kernel.
>>
>> There are lots of other functionality that is missing from yocto-bsp
>> kernel for Beaglebone. I suggest you take at the following repos and
>> scavenge for what you need :P
> First of all, this is meta-ti mailing list for the corresponding BSP. That's
> what Peter was asking for, comparing to Robert's Debian and Yocto reference
> BSPs, not the other way around.
>
> Second, Yocto reference BSP is that way for a reason - it's a reference BSP
> done with pure mainline kernel and u-boot components w/o any patching on top.
> That's its entire purpose. For anything else special, including performance
> tweaks, there are other BSPs available. If there is an issue with performance
> in meta-ti, we'll investigate it and try to match with Robert's BSP.

Yes, at this time meta-ti's BSP performs as well as I've seen any 
OE-based system, and gets several things right that meta-yocto-bsp does 
not (and one thing wrong that meta-yocto-bsp gets right, I think; still 
investigating, will follow-up when I'm sure).

I've also verified that performance with a native gcc 4.9.1 build on 
BeagleBone with hard float is poor, so it's not due to the way OE builds 
gcc.  I have several competing hypotheses to test.

But I'm still looking for a way to set the CPU frequency to the higher 
values supported on Beaglebone Black.  I had hoped meta-ti's would be 
able to do that, since it has bone vs boneblack device trees and u-boot 
detection.

Any hints where to look for clock settings?

Peter