Messages in this thread | | | Subject | Re: [PATCH -v7][RFC]: mutex: implement adaptive spinning | From | Peter Zijlstra <> | Date | Fri, 09 Jan 2009 10:28:25 +0100 |
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On Thu, 2009-01-08 at 11:13 -0800, Linus Torvalds wrote: > > On Thu, 8 Jan 2009, Chris Mason wrote: > > > > It is less fair though, the 50 proc parallel creates had a much bigger > > span between the first and last proc's exit time. This isn't a huge > > shock, I think it shows the hot path is closer to a real spin lock. > > Actually, the real spin locks are now fair. We use ticket locks on x86.
> We _could_ certainly aim for using ticket locks for mutexes too, that > might be quite nice.
Not really, ticket locks cannot handle a spinner going away - and we need that here.
I've googled around a bit and MCS locks (http://www.cs.rice.edu/~johnmc/papers/asplos91.pdf) look like a viable way to gain fairness in our situation.
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