Messages in this thread | | | Subject | Re: futex: wake explicit / wait on multiple memory locations | From | Davidlohr Bueso <> | Date | Wed, 23 Jul 2014 15:32:22 -0700 |
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On Wed, 2014-07-23 at 12:25 -0400, Milosz Tanski wrote: > I'm using futexes to control scheduling for a userspace application with multiple queues. > There's a global work queue and a specific pre-thread queue. And I would like to have a > choice between waking up any thread or a specific thread.
I'm afraid not: the api does not have a place for such an argument:
FUTEX_WAKE This operation wakes at most val processes waiting on this futex address (i.e., inside FUTEX_WAIT). The arguments timeout, uaddr2 and val3 are ignored.
In any case, when you start with this sort of thing it starts to get messy, real fast. You have to play games with the number of tasks to wakeup in a single futex wake call vs the "chosen" task(s).
> Is there are mechanism in the futex API by which I can control which thread to wake up.
Nope. FIFO and rt tasks always in front.
Thanks, Davidlohr
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