Messages in this thread | | | Subject | Re: Robust futexes | From | Rusty Russell <> | Date | Fri, 10 Mar 2006 10:17:48 +1100 |
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On Fri, 2006-02-17 at 08:23 -0800, Darren Hart wrote: > Rusty Russell wrote: > telling the kernel that the lock is the tid allows the > > kernel to do prio inheritence etc. in future. > > Priority Inheritance has come up a couple of times in relation to Ingo's new > LightWeight Robust Futexes. Ingo has said that PI is orthogonal to LWRF, but I > don't think we've heard if there are plans already in the works (or in his head > :-) for PI. Rusty's comment above reads as "the current LWRF implementation > cannot support PI" - is there something about it that makes PI impractical to > implement?
Hi Darren!
Ingo's approach is indeed orthogonal. But the obvious approach to PI etc is to tell the kernel who is holding the lock, by making the lock value == TID of the holder. If we are heading towards this anyway, the kernel could use this to implement robust mutexes, too, although not with a 100% guarantee (due to tid wrap). Ingo doesn't like that, though.
Hope that clarifies! Rusty. -- ccontrol: http://ozlabs.org/~rusty/ccontrol
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