Re: Real-Time Preemption, -RT-2.6.12-final-V0.7.50-24

From: Ingo Molnar <mingo@elte.hu>
To: "K.R. Foley" <kr@cybsft.com>
Cc: Daniel Walker <dwalker@mvista.com>,
	Karsten Wiese <annabellesgarden@yahoo.de>,
	linux-kernel@vger.kernel.org
Subject: Re: Real-Time Preemption, -RT-2.6.12-final-V0.7.50-24
Date: Tue, 12 Jul 2005 18:01:50 +0200	[thread overview]
Message-ID: <20050712160150.GA23943@elte.hu> (raw)
In-Reply-To: <42D3D7ED.7000805@cybsft.com>

* K.R. Foley <kr@cybsft.com> wrote:

> Ingo Molnar wrote:
> >* Daniel Walker <dwalker@mvista.com> wrote:
> >
> >
> >>I observed a situation on a dual xeon where IOAPIC_POSTFLUSH , if on, 
> >>would actually cause spurious interrupts. It was odd cause it's 
> >>suppose to stop them .. If there was a lot of interrupt traffic on one 
> >>IRQ , it would cause interrupt traffic on another IRQ. This would 
> >>result in "nobody cared" messages , and the storming IRQ line would 
> >>get shutdown.
> >>
> >>This would only happen in PREEMPT_RT .
> >
> >
> >does it happen with the latest kernel too? There were a couple of things 
> >broken in the IOAPIC code in various earlier versions.
> >
> >	Ingo
> 
> Is this why I have been able to boot the latest versions without the 
> noapic option (and without noticeable keyboard repeat problems) or has 
> it just been dumb luck?

yes, i think it's related - the IO-APIC code is now more robust than 
ever, and that's why any known-broken system would be important to 
re-check.

	Ingo