Get local CPU id

[Nicholas Krause]

On March 8, 2015 6:30:47 PM EDT, Valdis.Kletnieks at vt.edu wrote:
>On Sun, 08 Mar 2015 22:49:00 +0100, Maxime Ripard said:
>
>> On Sun, Mar 08, 2015 at 10:06:23PM +0300, Matwey V. Kornilov wrote:
>
>> > I would like to somehow obtain local CPU core ID in the interrupt
>> > handler function. I want to see how my interruptions are
>distributed
>> > among different CPU cores under different conditions.
>
>> > How should I do that?
>>
>> To answer strictly your question, like Nick said, smp_processor_id()
>> will work fine.
>>
>> However, you can do exactly what you want be reading
>/proc/interrupts,
>> that already provide the informations you are looking for.
>
>Clarification:  /proc/interrupts will give userspace that information.
>It is *not* recommended you try to read it from kernel space, much less
>from an interrupt context... :)
>
>
Does that matter through as all Matwey is interested in getting are the load balancing  among multiple cores on a smp based system under various workloads . I wouldn't mind recommending to just read proc/interrupts expect for it only being refreshed every 3 seconds to my knowledge by default and therefore not valid for getting per second data. Also this file doesn't explain the kernel's decision  to put what work on which core on a smp capable system  during interrupt context , which may also interest Matwey too. 
Just my opinion, 
Nick 
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