Subject: Re: [RFC] Summit interrupt routing patches
To: jamesclv@us.ibm.com
Date: Sat, 19 Jan 2002 01:18:09 +0000 (GMT)
Cc: alan@lxorguk.ukuu.org.uk (Alan Cox), linux-kernel@vger.kernel.org
In-Reply-To: <200201190018.g0J0Idq11657@butler1.beaverton.ibm.com> from "James Cleverdon" at Jan 18, 2002 04:18:37 PM
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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
Sender: linux-kernel-owner@vger.kernel.org

> idle CPUs.  If none are idle, then aim them at the CPUs running the "least 
> important" tasks.  Also, since each CPU's local APIC only has two interrupt 
> latches per `level' (the upper nibble of the IRQ's vector), it would be a 
> good idea to avoid sending IRQs to those CPUs that are already processing one.

Im not sure aiming at least important is worth anything. Aiming at idle 
processors on a box not doing power management seems easy providing you'll
accept 99.99% accuracy. Switch the priority up in the idle code, switch it
back down again before the idle task schedule()'s. If you hit during the
schedule well tough.

> soon.  I wonder if Marcelo is going to allow this kind of futzing around with 
> interrupt and scheduler code in 2.4....

Thats another reason to keep it small and clean.
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