Re: [PATCH v6] x86/hpet: Reduce HPET counter read contention

From: Dave Hansen
Date: Thu Aug 25 2016 - 14:50:18 EST

On 08/12/2016 05:59 PM, Waiman Long wrote:
> + * The lock and the hpet value are stored together and can be read in a
> + * single atomic 64-bit read. It is explicitly assumed that arch_spinlock_t
> + * is 32 bits in size.

This requirement forces us to give up all of the goodness of lockdep.
Is this strictly a performance optimization or is there some function
requirement behind it as well?