Messages in this thread | | | Date | Thu, 7 Sep 2006 04:32:44 -0400 | From | Jakub Jelinek <> | Subject | Re: NPTL mutex and the scheduling priority |
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On Thu, Sep 07, 2006 at 05:11:58PM +0900, Atsushi Nemoto wrote: > Three months after, I have tried kernel 2.6.18 with recent glibc. I > got desired results for pthread_mutex_unlock and > pthread_cond_broadcast, with PI-mutex. > > But pthread_cond_signal and sem_post still wakeup a thread in FIFO > order, as you can guess. > > With the plist patch (applied by hand), I can get desired behavior. > Thank you. But It seems the patch lacks reordering on priority > changes.
Yes, either something like the plist patch for FUTEX_WAKE etc. or, if that proves to be too slow for the usual case (non-RT threads), FIFO wakeup initially and conversion to plist wakeup whenever first waiter with realtime priority is added, is still needed. That will cure e.g. non-PI pthread_mutex_unlock and sem_post. For pthread_cond_{signal,broadcast} we need further kernel changes, so that the condvar's internal lock can be always a PI lock.
> <off_topic> > BTW, If I tried to create a PI mutex on a kernel without PI futex > support, pthread_mutexattr_setprotocol(PTHREAD_PRIO_INHERIT) returned > 0 and pthread_mutex_init() returned ENOTSUP. This is not a right > behavior according to the manual ... > </off_topic>
Why? POSIX doesn't forbid ENOTSUP in pthread_mutex_init to my knowledge.
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