Messages in this thread | | | Date | Fri, 19 Mar 2004 13:39:42 +0000 | From | Jamie Lokier <> | Subject | Re: spurious 8259A interrupt |
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Russell King wrote: > Interrupt handlers generally run with the CPU interrupt disable flag > cleared, so other interrupts can be serviced.
Indeed. But why? What's the advantage?
The obvious thought is it might improve latency of interrupt handlers which need reasonably low latency, when other handlers take a long time.
E.g. if the irq 1 handler takes a long time, multiple irq 2 interrupts can be serviced during it.
But that doesn't work, when there are no meaningful hardware priorities: an irq 2 handler can be interrupted by the long irq 1 handler, maybe before it gets to do anything useful, and then the irq 2 interrupt doesn't have low latency.
(I gather that irq priorities aren't especially meaningful on the x86 platform, as brought up on another thread recently).
Perhaps it works out statistically better.
Can you confirm that it does work out statistically better, or that there's something I didn't think of?
Thanks, -- Jamie - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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