On Thu, 18 Dec 2014, Jesse Brandeburg wrote:
> On Thu, 18 Dec 2014 23:42:03 +0100
> Thomas Gleixner <[email protected]> wrote:
>
> > On Thu, 18 Dec 2014, Jesse Brandeburg wrote:
> > > Enabling this function means that kernel drivers can include
> > > an initial affinity setting for the interrupt, instead of all
> > > interrupts starting out life on CPU0. It seems to have just
> > > been an oversight that it was not included.
>
> > And why needs this to be called from modules? Just because or is there
> > a legitimate reason? IOW, you forgot to describe the actual usecase.
>
> As stated above, the use case for my interest is making a network
> driver's many interrupt vectors not all show up on CPU0. Of course a
> user can work around this by manually tuning smp_affinity, but I have
> seen many reports from users and testers where the performance of the
> network was really bad due to all network interrupts on CPU0.
>
> This allows the driver to set a sane default smp_affinity value at
> driver load.
Fair enough. Overloaded brain missed parts of the explanation. :)
> Would you instead consider a patch where if a user calls the
> set_irq_affinity_hint that the initial affinity is set to the hinted
> value?
That would make a lot of sense, because you probably will set the
affinity hint anyway, right?
Thanks,
tglx
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