Messages in this thread | | | Date | Thu, 07 Sep 2006 17:11:58 +0900 (JST) | Subject | Re: NPTL mutex and the scheduling priority | From | Atsushi Nemoto <> |
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On Tue, 13 Jun 2006 01:06:28 +0900 (JST), Atsushi Nemoto <anemo@mba.ocn.ne.jp> wrote: > > > Really FUTEX_WAKE/FUTEX_REQUEUE can't use a FIFO. I think there was a patch > > > floating around to use a plist there instead, which is one possibility, > > > another one is to keep the queue sorted by priority (and adjust whenever > > > priority changes - one thread can be waiting on at most one futex at a > > > time). > > > > > > > The patch you refer to is at > > http://marc.theaimsgroup.com/?l=linux-kernel&m=114725326712391&w=2 > > Thank you all. I'll look into PI futexes which seems the right > direction, but I still welcome short term (limited) solutions, > hopefully work with existing glibc. I'll look at the plist patch.
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.
Are there any patch or future plan to address remaining wakeup-order issues?
<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>
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