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From: Peter Zijlstra on 30 Jun 2010 04:10
On Tue, 2010-06-29 at 15:32 +0100, Jan Beulich wrote:
> +static DEFINE_PER_CPU(arch_rwlock_t, spinning_rm_lock) = __ARCH_RW_LOCK_UNLOCKED;

why is that an arch_ lock?
why is that a rwlock?, those things are useless.
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From: Peter Zijlstra on 30 Jun 2010 05:00
On Wed, 2010-06-30 at 09:52 +0100, Jan Beulich wrote:
> > why is that a rwlock?, those things are useless.
>
> Because potentially each CPU's lock gets acquired for reading during
> unlock, while only the locking CPU's one needs to be acquired for
> writing during lock.

Can you say: scalability nightmare? but then its Xen code so who cares..

/me pretends he never saw it
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