On Tue, 2012-05-22 at 18:40 +0200, Thomas Gleixner wrote:

quoted

I'm all for benchmarks. But right now, making all readers pass through a
single mutex is a huge bottle neck for a lot of loads. Yes, they are
mostly Java loads, but for some strange reason, our customers seems to
like to run Java on our RT kernel :-p

I'm well aware that mmap_sem is a PITA but replacing one nightmare
with the next one is not the best approach.

Perhaps we could just change the mmap_sem to use this approach. Create a
new type of rwsem/lock for -rt that we can be picky about.

Yeah, mmap_sem is a real PITA and it would be nice to have a solution
that can be used until we can convert it to an RCU lock.

-- Steve