Re: [Linux-ia64] reader-writer livelock problem

From: Stephen Hemminger <>
Date: 2002-11-09 04:55:39
On Fri, 2002-11-08 at 09:34, David Howells wrote:
> > The normal way of solving this fairness problem is to make pending write
> > locks block read lock attempts, so that the reader count is guaranteed
> > to drop to zero as read locks are released.  I haven't looked at the
> > Linux implementation of rwlocks, so I don't know how hard this is to
> > do.  Or perhaps there's some other reason for not implementing it this
> > way?
> Actually implementing a fair spinlocks and fair rwlocks on the x86 arch are
> very easy (at least, if you have XADD it is). Any arch which has CMPXCHG can
> also do it, just not so easily.
> I've attached an implementation of a fair spinlock and an implementation of a
> fair rwlock (which can be compiled and played with in u-space).
> David

There are a selection of similar algorithms here:

How does yours compare?
Received on Fri Nov 08 09:56:19 2002

This archive was generated by hypermail 2.1.8 : 2005-08-02 09:20:10 EST