1Lightweight PI-futexes    4We are calling them lightweight for
3 reasons:    6 - in the user-space fastpath a PI-enabled futex
involves no kernel work    7   (or any other PI complexity) at
all. No registration, no extra kernel    8   calls - just pure
fast atomic ops in userspace.   10 - even in the slowpath, the
system call and scheduling pattern is very   11   similar to
normal futexes.   13 - the in-kernel PI implementation is
streamlined around the mutex   14   abstraction, with strict
rules that keep the implementation   15   relatively simple:
only a single owner may own a lock (i.e. no   16   read-write
lock support), only the owner may unlock a lock, no   17
recursive locking, etc.   19Priority Inheritance - why?   22The
short reply: user-space PI helps achieving/improving determinism
for   23user-space applications. In the best-case, it can help
achieve   24determinism and well-bound latencies. Even in the
worst-case, PI will   25improve the statistical distribution of
locking related application