Re: [RFC PATCH 0/3] restartable sequences: fast user-space percpu critical sections

[Andy Lutomirski]

On Wed, Jun 24, 2015 at 3:26 PM, Paul Turner <pjt@xxxxxxxxxx> wrote:
> This is a fairly small series demonstrating a feature we've found to be quite
> powerful in practice, "restartable sequences".
>

On an extremely short glance, I'm starting to think that the right
approach, at least for x86, is to implement per-cpu gsbase.  Then you
could do cmpxchg with a gs prefix to atomically take a percpu lock and
atomically release a percpu lock and check whether someone else stole
the lock from you.  (Note: cmpxchg, unlike lock cmpxchg, is very
fast.)

This is totally useless for other architectures, but I think it would
be reasonable clean on x86.  Thoughts?

I can elaborate if necessary.

--Andy
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