[RFC] ARM: Let GIC to route IRQs to any allowed CPUs

Hu Tao,
(Please avoid top posting)

-----Original Message-----
From: linux-arm-kernel-bounces at lists.infradead.org [mailto:linux-
arm-kernel-bounces at lists.infradead.org] On Behalf Of TAO HU
Sent: Wednesday, January 12, 2011 2:35 PM
To: Russell King - ARM Linux
Cc: TAO HU; linux-arm-kernel at lists.infradead.org
Subject: Re: [RFC] ARM: Let GIC to route IRQs to any allowed CPUs

Hi, Russell King

Thanks.

For "The result will be CPUs fighting over servicing such
interrupts."
What's the consequence? The performance downgrade?

Few problems I can see here.
1. Spurious interrupts will be seen by CPU who looses the IRQ race
2. When interrupts are targeted on two CPU's, and if one of the CPU is
in low power mode, the ON CPU will not see the interrupt till the     OFF
CPU becomes ON again.
3. Unnecessary wakeups on both CPUs which can screw up power savings.
4. prone to aggravate race conditions in the existing drivers.

Regards,
Santosh