Re: [PATCH] Enable polling for disabled screaming irqs

From: Ingo Molnar
Date: Fri Jul 18 2008 - 13:22:53 EST



* Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:

> When we disable a screaming irq we never see it again. If the irq
> line is shared or if the driver half works this is a real pain. So
> periodically poll the handlers for screaming interrupts.
>
> I use a timer instead of the classic irq poll technique of working off
> the timer interrupt because when we use the local apic timers
> note_interrupt is never called (bug?). Further on a system with
> dynamic ticks the timer interrupt might not even fire unless there is
> a timer telling it it needs to.
>
> I forced this case on my test system with an e1000 nic and my ssh
> session remained responsive despite the interrupt handler only being
> called every 10th of a second.

very nice idea!

I have applied your patch to tip/genirq, thanks Eric. We need more
kernel robustness features like this.

Ingo
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