On Mon, 30 Jul 2001, Bruce Momjian wrote:
> * Improve spinlock code, perhaps with OS semaphores, sleeper queue, or
> spining to obtain lock on multi-cpu systems
You may be interested in a discussion which happened over on
linux-kernel a few months ago.
Quite a lot of people want a lightweight userspace semaphore,
and for pretty much the same reasons.
Linus proposed a pretty interesting solution which has the
same minimal overhead as the current spinlocks in the non-
contention case, but avoids the spin where there's contention:
http://www.mail-archive.com/linux-kernel%40vger.kernel.org/msg39615.html
Matthew.