RE: [Xen-devel] [Patch 2 of 2]: PV-domain SMP performance Linux-part

["James Harper" <james.harper@xxxxxxxxxxxxxxxx>]

> On 16/01/2009 10:16, "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
wrote:
> 
> > I had previously wondered about optimizing spinlocks, my idea was
> > basically for Xen to set a bit in a structure to indicate what vcpus
are
> > currently scheduled, and my modified spinlock acquire routine would
> > check if the current vcpu wants a spinlock that is held by a
currently
> > unscheduled vcpu, and if so yield to Xen to let the other vcpu
schedule.
> 
> That's a lot more like our existing Linux pv_ops spinlock handling
> (yield/block instead of spin) than Juergen's patch (don't deschedule
me
> while in a critical section). The difference from what you suggest is
that
> we heuristically detect unscheduled lock holders by spinning a short
> while.
> 
> You can pv up your Windows spinlocks in the block-instead-of-spin way
> already (and yield-instead-of-spin is obviously even easier).
> 

But only in spinlocks that I 'own' completely right? I'm more concerned
about spinlocks that I share with Windows (eg in NDIS).

James

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