Leon Woestenberg wrote: > Hello, > > (including linux-rt-users in the CC:, irqthreads are on-topic there) Actually it's probably not interesting for this case. > > On Wed, Jul 2, 2008 at 1:02 PM, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote: >> Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> writes: >> >>>> how much of this would be obsoleted if we had irqthreads ? >>> I'm not sure irqthreads is what I want... >>> >> I also think interrupts threads are a bad idea in many cases because >> their whole "advantage" over classical interrupts is that they can >> block. Now blocking can be usually take a unbounded potentially long >> time. >> >> What do you do when there are more interrupts in that unbounded time? >> > If by irqthreads the -rt implementation is meant, isn't this what happens: > > irq kernel handler masks the source interrupt > irq handler awakes the matching irqthread (they always are present) > irqthread is scheduled, does work and returns > irq kernel unmasks the source interrupt I described this case. If the interrupt handler blocks for a long time (as Ben asked for) then the interrupts will not be handled for a long time. Probably not what you want. BTW this was not a criticsm of rt linux (in whose context irqthreads make sense as I explained) , just an explanation why they imho don't make sense (IMHO) in a non hard rt interruptible kernel and especially not to solve Ben's issue. > >> Create more interrupt threads? At some point you'll have hundreds >> of threads doing nothing when you're unlucky. >> > Each irqthread handles one irq. > So now new irq thread would spawn for any interrupt. It was a general description of all possible irqthreads. -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
