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    SubjectRe: Kernel WARNING: at net/core/dev.c:1330 __netif_schedule+0x2c/0x98()
    On Thu, Jul 24, 2008 at 09:06:51PM +1000, Nick Piggin wrote:
    > On Thursday 24 July 2008 20:55, Miklos Szeredi wrote:
    > > On Thu, 24 Jul 2008, Nick Piggin wrote:
    > > > Hey, something kind of cool (and OT) I've just thought of that we can
    > > > do with ticket locks is to take tickets for 2 (or 64K) nested locks,
    > > > and then wait for them both (all), so the cost is N*lock + longest spin,
    > > > rather than N*lock + N*avg spin.
    > >
    > > Isn't this deadlocky?
    > >
    > > E.g. one task takes ticket x=1, then other task comes in and takes x=2
    > > and y=1, then first task takes y=2. Then neither can actually
    > > complete both locks.
    >
    > Oh duh of course you still need mutual exclusion from the first lock
    > to order the subsequent :P
    >
    > So yeah it only works for N > 2 locks, and you have to spin_lock the
    > first one... so unsuitable for scheduler.

    Or sort the locks by address or some such.

    Thanx, Paul


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