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Re: [Xen-devel] [PATCH 1/4] xen/arm: gic: Ensure we have an ISB between ack and do_IRQ()

Hello Andre,

On 03.12.18 15:46, Andre Przywara wrote:
Well, you should be scared of the old VGIC locking scheme instead ;-)
Old VGIC locking is more mazy, indeed.

Apart from the vgic_queue_irq_unlock() function, the rest of the new
locking scheme is much clearer.
I agree,

Yes, but effectively this virtually never happens, as you have rarely
more than four pending IRQs at the same time.
I've checked that. Just put a perfcounter there. Surprisingly it happens few times per run under my simplified conditions. Should check them with more complex multimedia use-cases on a different setup.

I had patches lying around to improve this part, just never got around
to post, especially with only little rationale.
If you are interested, I can dig them out, though I am not sure how
relevant this is.
I'm interested, for sure. I'm pretty sure we will need them when we have multimedia scenarios on the table.

Andrii Anisov.

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