Re: any fairness in NTPL pthread mutexes?

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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 [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux