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Re: Next round: revised futex(2) man page for review

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On Tue, 2015-07-28 at 22:45 +0200, Peter Zijlstra wrote:
> Also, this code seems to use plist, which means it won't do the right
> thing for SCHED_DEADLINE either.

Ick, I don't look forward to seeing nice futex plists converted into
rbtrees. As opposed to, eg. rtmutexes, there are a few caveats:

- Dealing with the top_waiter in rtmutexes is always easy, but in
futexes we need to deal with keys, so caching the leftmost won't work as
nicely.

- This will bloat things like futex_wake, where O(logN) is not suited
for FIFO iteration. And iterating linked lists is, in essence, all that
we really do when calling futex(2).

I have to wonder about the extra overhead added by these points.  I do
understand the dl concern, nonetheless.

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Re: Next round: revised futex(2) man page for review Peter Zijlstra <peterz@infradead.org> - 2015-07-28 22:50 +0200
  Re: Next round: revised futex(2) man page for review Thomas Gleixner <tglx@linutronix.de> - 2015-07-28 23:10 +0200
  Re: Next round: revised futex(2) man page for review Davidlohr Bueso <dave@stgolabs.net> - 2015-07-29 04:10 +0200

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