Re: why mprotect(PROT_SEM) ?

In message <[email protected]> yo
u write:
> 
> > That's good news then, we can remove the mprotect syscall 
> > from the NGPT 
> > runtime library if the kernel futex code is doing it. Still 
> > might be an
> > advantage in allocating the user-mode futex structs in the same page, 
> > should yield less pinned pages.
> 
> Well, I am not that sure, we'd need Rusty to confirm that. AFAIK, this could
> be right, as the vcache mechanism should take care of it, but I am not still
> that sure we can just wipe it out [for 2.4 kernels]. 

No, vcache solves a different problem.

But Linus has declared that those (rate) platforms which don't have
sane cache architectures can just not implement futexes, so you can
drop it and worry about it when they want NGPT on one of them
(ie. never).

Rusty.
--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.