RE: [PATCH][2.4] generic cluster APIC support for systems with m ore than 8 CPUs

["Martin J. Bligh" <mbligh@aracnet.com>]

> Some platforms (like certain ES7000s) won't tolerate any bit masks
> programmed into the RTE because their balancing is done entirely in
> hardware, similar to XTPR mechanism for Fosters. For those I suggest to
> have an escape door, in the form of boot parameter such as
> "irq_balance=no". It was suggested to us by SuSE and worked great - I
> could turn it off in our platform code unconditionally. It could also
> help those who can use irq balancing as is but might want to implement
> their own balancing schema.

Having a boot-time parameter is useful, but I'd like it to default to off
without a paramater for the platforms where it's just broken. At the
moment there's an "if (clustered_apic_mode) return;" stuck at the top
of balance_irq, the latest series of patches changes that to
"if (no_balance_irq) return;", which is set by NUMA-Q. If we can set
up no_balance_irq to default correctly, but be possibly overridden by
the boot-time parameter, I think we'd have the best of both worlds.

M.