On Mon, 2012-07-16 at 12:02 -0400, Steven Rostedt wrote: 

On Mon, 2012-07-16 at 04:02 +0200, Mike Galbraith wrote:

quoted

quoted

Great, thanks!  I got stuck in bug land on Friday.  You mentioned
performance problems earlier on Saturday, did this improve performance?

Yeah, the read_trylock() seems to improve throughput.  That's not
heavily tested, but it certainly looks like it does.  No idea why.

Ouch, you just turned the rt_read_lock() into a spin lock. If a higher
priority process preempted a lower priority process that holds the same
lock, it will deadlock.

Hm, how, it's doing cpu_chill()?

I'm not sure why you would get a performance benefit from this, as the
mutex used is an adaptive one (failure to acquire the lock will only
sleep if preempted or if the owner is not running).

I'm not attached to it, can whack it in a heartbeat.. especially so it
the thing can deadlock.  I've seen enough of those of late.

We should look at why this performs better (if it really does).

Not sure it really does, there's variance, but it looked like it did.

-Mike