Messages in this thread | | | Subject | Re: [RFC][PATCH] irq: remove IRQF_DISABLED | From | Benjamin Herrenschmidt <> | Date | Fri, 06 Mar 2009 19:58:42 +1100 |
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On Mon, 2009-03-02 at 09:11 -0800, Linus Torvalds wrote: > > On Mon, 2 Mar 2009, Peter Zijlstra wrote: > > > > Would you be willing to take such a patch? > > Yes - some day. > > The "irq's disabled fastpath" thing has been there since pretty much day > one, because some irq handlers always wanted it. Making it the default > (and the only choice) is fine.
.../...
I tend to disagree... (not -that- strongly but I felt like saying it anyway :-) some archs have a reasonably nice support in the PIC for interrupt priorities, allowing higher priority interrupts to "preempt" lower priority ones, which this would effectively render useless.
Also, while yes, I agree, interrupts handlers -should- be short in practice IDE is far from being the only example where this is not the case and so we would delay timer interrupts for example for a significant amount of time (or serial, that's another good example).
Also, we use the priority on some platform to have a high priority used as a kind of "debugger" NMI .. ie, we don't have a real NMI but it's better than nothing and here too, this would break it.
I don't see us having such a strong benefit from this... in fact, with things like -rt, interrupts get moved to threads no ? Thus they typically run with interrupts enabled... why have a different behaviour on non-rt ? or I am missing something ? (I'm not terribly familiar with the -rt stuff here so I probably am missing something).
Cheers, Ben.
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