IRQ and CPU Affinity on new Kernels

[Keith Busch]

On Thu, Dec 03, 2015 at 06:35:55PM -0500, Angelo Brito wrote:
> Hello Gentlemen,
> 
> We had some problems with a controller and some commands were missing
> (timeouts and cancelling I/O).
>
> I noticed that some interruptions were handled by different CPUs, like
> in this example:

I doubt the interrupt affinity you're seeing could have anything
to do with timeouts or missing commands.

There is a small window of time when a disk is initially brought online,
but before the affinity hints are provided. Because of that, even if
you properly affinitize all irqs to use the driver's hint, you'll likely
see a few irqs on non-optimal CPU.