RE: [Xen-devel] [PATCH] Yield to VCPU hcall, spinlock yielding

["Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>]

> You can only use spinlock accounting for dealing with locking 
> issues in kernel (unless you are willing to change 
> application level programs and libs).  If preemption 
> notification overhead is not prohibitive, the fact that it 
> solves the application problem as well as the kernel problem 
> seems like a compelling advantage over spinlock accounting, 
> doesn't it? 

Orran, 

Are you assuming the pre-emption notification is going to get propagated
to user-space as a signal, and that user space applications would be
modified to take advantage of the signal? (possibly this could be hidden
in the pthread library?} Since the kernel doesn't know when user space
has an application lock or not, that's going to be a lot of signals. 

Cheers,
Ian

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