linux-kernel - Re: [PATCH] Enable polling for disabled screaming irqs

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Message-ID: <20080718172231.GM6875@elte.hu>
Date:	Fri, 18 Jul 2008 19:22:31 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	"Thomas Gleixner <tglx@...utronix.de> Gleixner" <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Enable polling for disabled screaming irqs


* Eric W. Biederman <ebiederm@...ssion.com> 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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