On 11/19/2012 06:36:42 AM, Alexander Graf wrote:
On 14.11.2012, at 05:32, Paul Mackerras wrote:
> +/*
> + * Note modification of an HPTE; set the HPTE modified bit
> + * if it wasn't modified before and anyone is interested.
> + */
> +static inline void note_hpte_modification(struct kvm *kvm,
> + struct revmap_entry *rev)
> +{
> + if (!(rev->guest_rpte & HPTE_GR_MODIFIED) &&
> + atomic_read(&kvm->arch.hpte_mod_interest))
Aren't atomic reads expensive?
No, it's a simple load instruction (done with inline asm so the
compiler can't break it up into smaller loads).
-Scott
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