Re: RFC: MSI/MSI-X implementation

[David Young <dyoung%pobox.com@localhost>]

On Thu, Nov 13, 2014 at 12:41:38PM +0900, Kengo NAKAHARA wrote:
> (2014/11/13 11:54), David Young wrote:
> >On Fri, Nov 07, 2014 at 04:41:55PM +0900, Kengo NAKAHARA wrote:
> >>Could you comment the specification and implementation?
> >
> >The user should not be on the hook to set processor affinity for the
> >interrupts.  That is more properly the responsibility of the designer
> >and OS.
> 
> I wrote unclear explanation..., so please let me redescribe.
> 
> This MSI/MSI-X API *design* is independent from processor affinity.
> The device dirvers can use MSI/MSI-X and processor affinity
> independently of each other. In other words, legacy interrupts and
> INTx interrupts can use processor affinity still. Furthermore,
> MSI/MSI-X may or may not use processor affinity.

MSI/MSI-X is not half as useful as it ought to be if a driver's author
cannot spread interrupt workload across the available CPUs.  If you
don't mind, please share your processor affinity proposal and show how
it works with interrupts.

Dave

-- 
David Young
dyoung%pobox.com@localhost    Urbana, IL    (217) 721-9981