Messages in this thread | | | Subject | Re: [Linux-ia64] reader-writer livelock problem | From | Stephen Hemminger <> | Date | 08 Nov 2002 09:55:39 -0800 |
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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: http://www.cs.rochester.edu/u/scott/synchronization/pseudocode/rw.html#s_f
How does yours compare?
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