On Thu, 2010-12-09 at 22:39 -0800, Michel Lespinasse wrote:
> I think rwsem_is_contended() actually sounds better than fiddling with
> constants, but OTOH maybe the mlock use case is not significant enough
> to justify introducing that new API.
Right, so I don't see the problem with _is_contended() either. In fact,
I introduce mutex_is_contended() in the mmu_preempt series to convert
existing (spin) lock break tests.
If you want to do lock-breaks like cond_resched_lock() all you really
have is *_is_contended(), sleeping locks will schedule unconditional.
int cond_break_mutex(struct mutex *mutex)
{
int ret = 0;
if (mutex_is_contended(mutex)) {
mutex_unlock(mutex);
ret = 1;
mutex_lock(mutex);
}
return 1;
}
Or more exotic lock breaks, like the mmu-gather stuff, which falls out
of its nested page-table loops and restarts the whole affair.
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