On Fri, 2009-03-06 at 20:59 +1100, Benjamin Herrenschmidt wrote: > > If you have distinct interrupt priorities, you can > > > > 1) provide an interrupt stack for each priority > > 2) mask all lower priorities when handling one > > > > Would that not work? > > The PIC does that already. IE. it will only interrupt again before > ->eoi() for an interrupt of a higher priority. But by using > IRQF_DISABLED, you mask interrupts in the core, and thus effectively > completely prevents the whole thing. > > > The problems with enabling irqs in hardirq handlers are that you get > > unlimited irq nesting, which is bad for your stack, furthermore, somehow > > people thing it makes things 'faster' because the irq-off latency goes > > down. > > No, you don't get unlimited IRQ nesting, at least not on sane archs with > a decent PIC that does things like what I described above :-) Right, welcome to x86 ;-) Sounds to me we need to extend genirq a bit... Thomas? -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
