On Wed, 7 Jan 2009, Linus Torvalds wrote: > On Wed, 7 Jan 2009, Steven Rostedt wrote: > > > > What would be interesting is various benchmarks against all three. > > > > 1) no mutex spinning. > > 2) get_task_struct() implementation. > > 3) spin_or_sched implementation. > > One of the issues is that I cannot convince myself that (2) is even > necessarily correct. At least not without having all cases happen inder > the mutex spinlock - which they don't. Even with the original patch, the > uncontended cases set and cleared the owner field outside the lock. True. I need to keep looking at the code that is posted. In -rt, we force the fast path into the slowpath as soon as another task fails to get the lock. Without that, as you pointed out, the code can be racy. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
