OK. That would be interesting to see with the mmap_sem change,
because that should increase scalability.
Yeah. That's funny, because it means either there is some
contention on the mmap_sem (or ptl) at 1 thread, or that my
patch alters the uncontended performance.
I don't see why parallelism should come into it at 1 thread, unless
MySQL is parallelising individual transactions. Anyway, I'll try to do
some more digging.
SUSE Labs, Novell Inc.