[meta-freescale] linux-imx-3.10.9 with preempt-rt patch

Jacob Kroon jacob.kroon at gmail.com
Mon Mar 24 09:48:45 PDT 2014

Hi Otavio,

On Mon, 24 Mar 2014, Otavio Salvador wrote:

> Hello Jacob,
> On Mon, Mar 24, 2014 at 12:37 PM, Jacob Kroon <jacob.kroon at gmail.com> wrote:
>> On Mon, 24 Mar 2014, Otavio Salvador wrote:
>>> On Mon, Mar 24, 2014 at 11:27 AM, Jacob Kroon <jacob.kroon at gmail.com>
>>> wrote:
>>>> Some further progress on the RT-patch support that I forgot.
>>>> The oops seemed to be caused by a comparison mixup of NULL or -1.
>>>> See attached patch. Comments would be appreciated.
>>> I don't use the RT patch but for your best profit of it, would be good
>>> if you could focus the 3.10.17 kernel in git.freescale.com as this is
>>> the basis of the upcoming 3.10.17-1.0.0 GA release. This would allow
>>> for people to easily use your patch :D
>> Right, I forgot to mention, I've been applying this on top of linux-imx
>> 3.10.17 (ec1af9f898d234001d8fc7d720382de34cb6580f) +
>> patch-3.10.17-rt12.patch.
> Have you did and measurement test with and without those patches? I
> think this would be of great help.

I have done some testing using various tools from "rt-tests" package.
The patch does show a big improvement when looking at the numbers from
"cyclictest", max. peak of ~150 us in wakeup-latency for a high-priority
realtime thread (compared to milliseconds even with a PREEMPT kernel), 
while loading the system in all the possible ways I could think of,
including utilizing the GPU. This was on a Wandboard Solo.


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