Re: spinlock requests (was RE: [Xen-devel] [Patch] don't spin with irq disabled)

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 31/03/2009 14:40, "Juergen Gross" <juergen.gross@xxxxxxxxxxxxxxxxxxx>
wrote:

> Dan Magenheimer wrote:
>> Thanks Juergen.  Do you know of any GPLv2 code that implements
>> this improved rwlock solution?  (I don't think Linux does,
>> does it?)
> 
> Good question.
> I just looked into the Linux code and decided not to analyse it. :-)
> I have implemented a solution for our BS2000 system on Xen. It is just
> a rather simple state machine using the cmpxchg instruction for the
> update of the (structured) lock word.
> If there is common interest for this solution I could prepare a patch.

If we care that much about fairness we should use ticket- or queue-based
locks. I don't believe any of our locks are contended enough to be a
concern. If they were, that would be a concern in itself.

 -- Keir



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel