Hello, Firstly, may I apologise as I am not a member of the LKML, and ask that I be CC'd in any responses that may be forthcoming.
My question concerns the following patch which was incorporated into the 2.6.22 kernel (quoted from that change log): >Today, all threads waiting for a given futex are woken in FIFO >order (first waiter woken first) instead of priority order. > >This patch makes use of plist (pirotity ordered lists) instead >of simple list in futex_hash_bucket. > >All non-RT threads are stored with priority MAX_RT_PRIO, causing >them to be woken last, in FIFO order (RT-threads are woken first, >in priority order). > >Signed-off-by: Sebastien Dugue <[EMAIL PROTECTED]> >Signed-off-by: Pierre Peiffer <[EMAIL PROTECTED]> After updating to this version of the kernel, I was able to observe the above fix, where multiple RT threads invoking pthread_cond_wait(), and the highest priority thread will acquire the mutex first, after the thread holding the mutex calls pthread_cond_signal(); pthread_mutex_unlock() However, since kernel 2.6.23, it seems that the functionality relating to this "priority based wakeup" has disappeared. I understand there have been significant changes in this kernel concerning the "Completely Fair Scheduler" replacing the "mainline" scheduler; however my understanding is that the RT functionality would be preserved. This does not appear to be the case based on repeating the experiment described above. I was wondering if this functionality is considered no longer desirable/necessary? If not, is it anticipated that this functionality could/would be included in a later kernel? Regards, Mark Hansen -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
