Re: Fast User Space Mutexes (aka Futexes)

[Hiten Pandya <hmp@xxxxxxxxxxxxx>]

Bill Huey (hui) wrote:

> On Tue, Oct 21, 2003 at 04:05:04PM +0100, Hiten Pandya wrote:
>
> > Hi Gang,
> >
> > Sinces the day when Matt was interviewed by the SlashNET people, a 
> > couple of questions arised as to the implementation of Futexes for the 
> > new libcr which is going to be written.
> >
> > I am sending this mail as an opening to this discussion.  Hopefully, 
> > some of the Linux seniors scanning this lists (Rik et al) will provide 
> > some comments and suggestions on this topic.
> >
> > IMHO, from the way Futexes work, it would be great to have an 
> > implementation of it for DragonFly.  For those of you wondering what 
> > Futexes are exactly, please refer to [1], as thats the most complete 
> > documented information I could find, apart from the Ottawa proceedings 
> > (Rusty Russell).
> >
> > [1] - http://www.catfive.org/cgi-bin/man2web?program=futex&section=4
>
>
> http://people.redhat.com/drepper/futex.pdf
>
> Better documentation on how it's used and some implementation issues with
> glibc. The problem with futex's in the context of dfBSD is that it's
> used for their 1:1 threading model, which is different than the M:N
> stuff that's being done recently. I think it's essential to think about

	I recall Rusty Russell added the Asynchronous interface to the
	Futex interface, yes, I am referring to the FUTEX_AWAIT and
	friends.  It was needed for the NGPT work, since it is M:N
	effectively.

	Regards,

--
Hiten Pandya
hmp@xxxxxxxxxxxxx