[rfc][patch] increase irq 12 penalty

[rfc][patch] increase irq 12 penalty

[Jeff Garzik]

This is something that Red Hat ships in its kernel.  I was thinking it
belonged upstream, but was told "Alan rejected it; reason forgotten" :)

Here is the logic for the patch:
> It makes the "pick any IRQ" code in the kernel not pick irq12 by default.
> irq12 is the ps/2 irq that gets emulated by smm on laptops.
> Using that can be sudden death on several machines.
> So the patch makes the cost of using it higher than the other irq's.

Arjan, one of our RH kernel rpm maintainers, also adds:
> for all I know it's totally wrong
> but it fixed some machines and it doesn't seem to break any

So I thought I would send it to lkml for comments.  RH has been carrying
this for a while...


diff -urNp linux-1090/arch/i386/kernel/pci-irq.c linux-1100/arch/i386/kernel/pci-irq.c
--- linux-1090-arch-i386/kernel/pci-irq.c	
+++ linux-1100-arch-i386/kernel/pci-irq.c	
@@ -36,7 +36,7 @@ unsigned int pcibios_irq_mask = 0xfff8;
 
 static int pirq_penalty[16] = {
 	1000000, 1000000, 1000000, 1000, 1000, 0, 1000, 1000,
-	0, 0, 0, 0, 1000, 100000, 100000, 100000
+	0, 0, 0, 0, 2500, 100000, 100000, 100000
 };
 
 struct irq_router {



[note, patch pathnames mangled to prevent immediate application :)]