Re: Performance regression from switching lock to rw-sem foranon-vma tree

[Peter Zijlstra]

On Tue, Jul 23, 2013 at 11:45:13AM +0200, Ingo Molnar wrote:
> Why not just try the delayed addition approach first? The spinning is time 
> limited AFAICS, so we don't _have to_ recognize those as writers per se, 
> only if the spinning fails and it wants to go on the waitlist. Am I 
> missing something?
> 
> It will change patterns, it might even change the fairness balance - but 
> is a legit change otherwise, especially if it helps performance.

Be very careful here. Some people (XFS) have very specific needs. Walken
and dchinner had a longish discussion on this a while back.
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