[illumos-Developer] Available MSI(-x) interrupt limit.

[Dmitry Yusupov]

This seems like not logical way to fix ill driver... :-) Instead of
harming overall system performance we should fix the driver(s). And
those vendors who ships Illumos can apply limiting settings if they
care. I would guess that in most cases they will not use Illumos with
devices/drivers which would consume all the interrupts and would rather
prefer to focus the driver...

Why don't we reverse this default setting from max to min ?

> -----Original Message-----
> From: Garrett D'Amore [mailto:garrett at nexenta.com]
> Sent: Tuesday, June 07, 2011 7:51 AM
> To: Alexey Zaytsev
> Cc: illumos-dev
> Subject: Re: [illumos-Developer] Available MSI(-x) interrupt limit.
> 
> Yes.    The limit comes from the fact that ill behaved devices/drivers
could
> easily consume all the interrupts on a system, preventing other
devices from
> attaching.  There was a recent rearchitecture of the interrupt code
> specifically for MSI-X that offers far more interrupt vectors to
devices, in
> exchange for the device registering a callback indicating a
willingness to
> return interrupts back to the system when they become scarce.
> 
> There's also a legacy override somewhere that you can use for specific
> devices, but it isn't documented.  I don't remember the name of the
override,
> but it can grow the set up to 8.
> 
>   -- Garrett D'Amore
> 
> On Jun 7, 2011, at 5:49 PM, "Alexey Zaytsev"
<alexey.zaytsev at gmail.com>
> wrote:
> 
> > Hey.
> >
> > Any ideas, what's the reason to have the 2 msi per device limit?
> > It's been there from the start of the history.
> >
> > https://github.com/illumos/illumos-
> gate/blob/master/usr/src/uts/common/os/ddi_intr_impl.c#L296
> > https://github.com/illumos/illumos-
> gate/blob/master/usr/src/uts/common/os/ddi_intr_impl.c#L40
> > https://github.com/illumos/illumos-
> gate/blob/master/usr/src/uts/common/sys/ddi_intr_impl.h#L146
> >
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