Re: [Xen-devel] Performance overhead of paravirt_ops on nativeidentified

[Jeremy Fitzhardinge]

Jan Beulich wrote:
> Wouldn't a third solution be to use ticket spinlocks everywhere, i.e. eliminate
> the current indirection, and replace it by an indirection for just the contention
> case? As I view it, the problem for Xen aren't really the ticket locks by
> themselves, but rather the extra spinning involved, which is of concern only
> if a lock is contended. We're using ticket locks quite happily in our kernels,
> with directed instead of global wakeup from the unlock path.
Do you have a patch to illustrate what you mean?  How do you keep track 
of the target vcpu for the directed wakeup?  Are you using the 
event-poll mechanism to block?

   J
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