Re: [RFC patch 0/5] futex: Allow lockless empty check of hashbucketplist in futex_wake()

[Linus Torvalds]

On Sun, Dec 1, 2013 at 12:39 PM, Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote:
>
> Last time I checked, private futexes were used when appropriate.
>
> "strace -e futex" mainly show _PRIVATE uses.

Yeah, pthread mutexes seem to do it. Sadly we don't do it for
mm_release(), so the case of clear_child_tid doesn't trigger it, and
that happened to be what I tested (I did "git diff" with the threaded
pre-population of the stat data).  And we can't change that because
it's ABI. Sad.

So we do have a couple of corner cases where we *could* use the
private ones but don't. But I guess that thread creation/exit is
heavy-weight enough that that particular one doesn't really matter.

               Linus
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