On Fri, Jun 30, 2017 at 08:04:21AM +0200, Greg KH wrote: > On Thu, Jun 29, 2017 at 12:01:34PM -0700, Todd Kjos wrote: > > The binder driver uses a global mutex to serialize access to state in a > > multi-threaded environment. This global lock has been increasingly > > problematic as Android devices have scaled to more cores. The problem is > > not so much contention for the global lock which still remains relatively > > low, but the priority inversion which occurs regularly when a lower > > priority thread is preempted while holding the lock and a higher priority > > thread becomes blocked on it. These cases can be especially painful if the > > lower priority thread runs in the background on a slow core at a low > > frequency. This often manifests as missed frames or other glitches. > > > > For several years, a hacky solution has been used in many Android devices > > which disables preemption for most of the time the global mutex is held. > > This dramatically decreased the cases of glitches induced by priority > > inversion and increased the average throughput for binder transactions. > > > > Moving to fine-grained locking in this patchset results is a cleaner > > and more scalable solution than the preempt disable hack. Priority > > inversion is decreased significantly. > > Yeah, it is great to see this work done! I'll review these on Monday, > sorry, am traveling at the moment... All now queued up in my trees. thanks, greg k-h _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
