Re: [v2] powerpc: handle simultaneous interrupts at once

On Mon, 2017-06-05 at 20:21 +1000, Michael Ellerman wrote:

On Thu, 2017-03-16 at 08:55:45 UTC, Christophe Leroy wrote:

quoted

It often happens to have simultaneous interrupts, for instance
when having double Ethernet attachment. With the current
implementation, we suffer the cost of kernel entry/exit for each
interrupt.

This patch introduces a loop in __do_irq() to handle all interrupts
at once before returning.

Signed-off-by: Christophe Leroy <redacted>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/45cb08f4791ce6a15c54598b4cb73d

Hrm, I hadn't noticed that patch...

We used to do that and then removed the code for it. There's a cost,
sometimes noticeable, to an extra call to ppc_md.get_irq.

Why not have your get_irq (or eoi) implementation set a per-cpu
requesting a new spin of the loop ?

We could move the xive force replay stuff to use the same thing.

Ben.