Re: Kernel thread's CPU affinity with isolcpus kernel boot argument

[Mathias Koehrer <mathias.koehrer@etas.com>]

Am 25.02.2016 um 15:43 schrieb Josh Cartwright:
> On Thu, Feb 25, 2016 at 03:18:06PM +0100, Sebastian Andrzej Siewior wrote:
>> * Mathias Koehrer | 2016-01-15 12:15:28 [+0100]:
>>
>>> However, I noticed that most kernel threads use the affinity mask 0xff.
>>> I can change this by using ???taskset???. However, I am wondering if
>>> there is mechanism that forces the kernel to consider the value of
>>> ???isolcpus??? also for kernel threads.
>>
>> not that I am aware of. There are a few per-CPU threads which have to
>> stay the way they are. I would have expected that others like kworker/u*
>> respect the isol CPUs and stay away.
>
> I suppose the higher level question to Mathias is: are you seeing these
> threads perturb your application?  Or, are you just observing they are
> affinitized to isolcpus?
We use isolcpus=1-31 to reserve all cores but core 0 for real time stuff.
I just noticed, that some kernel threads have an affinity to cores > 0.
So far I did not observe any disturbance from these threads.

Thanks

Mathias