Messages in this thread | | | Subject | Re: any fairness in NTPL pthread mutexes? | From | Lee Revell <> | Date | Wed, 02 Nov 2005 13:47:54 -0500 |
| |
On Wed, 2005-11-02 at 17:47 +0000, James Courtier-Dutton wrote: > Christopher Friesen wrote: > > > > I'm using NPTL. > > > > If I have a pthread mutex currently owned by a task, and two other tasks > > try to lock it, when the mutex is unlocked, are there any rules about > > the order in which the waiting tasks get the mutex (ie priority, FIFO, > > etc.)? > > > > Thanks, > > > > Chris > > - > > There is no fairness at all. It's currently not designed to be fair > either. The reasons for this I can't remember, but there was talk at the > KS about it and I just remember the answer. I think it had something to > do with "If we implement fairness, general locking performance will drop > and we prefer performance over fairness." > > The solution is to modify your program so as not to rely on fairness.
Or try RT-NPTL + realtime and robust mutexes kernel patches. The problem and solution is described in more detail here:
http://developer.osdl.org/dev/robustmutexes/src/fusyn.hg/Documentation/fusyn/fusyn-why.txt
Lee
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |