On Mon, Jul 16, 2012 at 10:26:08AM -0600, Mike Galbraith wrote: > On Mon, 2012-07-16 at 12:02 -0400, Steven Rostedt wrote: > > On Mon, 2012-07-16 at 04:02 +0200, Mike Galbraith wrote: > > > > > > 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. > I'd use a benchmark that is more consistent than dbench for this. I love dbench for generating load (and the occasional deadlock) but it tends to steer you in the wrong direction on performance. -chris -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
