On Fri, Jan 8, 2016 at 3:15 PM, Andy Lutomirski [off-list ref] wrote:

Please play around and suggest (and run?) good benchmarks.  It seems
to save around 100ns on cross-process context switches for me.

Interesting. There was reportedly (I never saw it) a test-patch to use
pcids inside of Intel a couple of years ago, and it never got outside
because it didn't make a difference.

Either things have changed (newer hardware with more pcids perhaps?)
or you did a better job at it.

              Linus