Re: Futex manpages out of date

[Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>]

On Mon, 2010-01-18 at 17:40 +0100, Petr Baudis wrote:
> On Fri, Jan 15, 2010 at 06:11:24PM +0100, Peter Zijlstra wrote:
> > On Fri, 2010-01-15 at 08:58 -0800, Darren Hart wrote:
> > > The futex man-pages (2,7) from version 3.15-1 and at least a few earlier
> > > versions are considerably out of date with respect to the current
> > > implementation. They don't document newer op codes, such as:
> > > 
> > > FUTEX_WAIT_BITSET
> > > FUTEX_WAKE_BITSET
> > > FUTEX_WAKE_OP
> > > FUTEX_LOCK_PI
> > > FUTEX_UNLOCK_PI
> > > FUTEX_WAIT_REQUEUE_PI
> > > FUTEX_CMP_REQUEUE_PI
> > > 
> > > These new wait op codes now use absolute timeouts, while the original
> > > FUTEX_WAIT uses a relative timeout. Lastly, and most importantly, glibc
> > > has removed the futex() wrapper to syscall(SYS_futex, ...). With that in
> > > mind, would people prefer that we simply remove the futex man-pages
> > > (2,7)?
> > 
> > A readable text about the interaction between the futex value and the
> > various futex ops and how to build proper locking primitives with them
> > would be helpful I think, however doing that in the form of a locking
> > library (as has been suggested at KS) seems plenty fine to me.
> > 
> > Readable code is much better than rambling English at conveying this
> > stuff.
> 
> http://people.redhat.com/drepper/futex.pdf is pretty good description,
> unfortunately also outdated by now. Perhaps it would be interesting to
> convert this into some kind of wiki form with Ulrich's permission?

People keep saying that, but I found it highly unreadable.

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