linux-kernel - Re: question about the limited interrupt vector resource on a single cpu

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Date:   Wed, 6 Jun 2018 11:34:43 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Pingfan Liu <kernelfans@...il.com>
cc:     x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: question about the limited interrupt vector resource on a single
 cpu

On Wed, 6 Jun 2018, Pingfan Liu wrote:

> On Wed, Jun 6, 2018 at 5:15 PM, Thomas Gleixner <tglx@...utronix.de> wrote:
> > On Wed, 6 Jun 2018, Pingfan Liu wrote:
> >
> >> For x86, there is around 200 vectors left for external device on a
> >> single logic cpu.
> >>
> >> Is there any case that we exhaust them in real world, and is it worth to fix?
> >
> > Exhaustion is unlikely, but how would you fix it? The vector space per CPU
> > is limited by hardware not software.
> >
> Playing some trick on iommu, we can use it to identify the irq requester.

But what's the point? If you have more than 200 device interrupts on a
single CPU, then you surely have other problems than that.

What kind of problem are you trying to solve?

Thanks,

	tglx