Re: furwocks: Fast Userspace Read/Write Locks

[Rusty Russell]

In message <[e-mail]> you write:
> Rusty Russell wrote:
> > To clarify: I'd love this, but rwlocks in the kernel aren't even
> > vaguely fair.  With a steady stream of overlapping readers, a writer
> > will never get the lock.
> > 
> > Hope that clarifies,
> 
> 
> But you talk about the current implementation, don't you?
> Is there something to prevent an implementation of rwlocks in the
> kernel, where a wrlock will lock (postponed) further rdlock requests?

It's proven hard to do without performance impact.  Also, we can't do
rw semaphores in a single word: you need two.

Disproving me by implementation VERY welcome!

Hope that helps,
Rusty.
--
  Anyone who quotes me in their sig is an idiot. -- Rusty Russell.