Re: [PATCH v2 0/4] Fix accessed bit tracking

Lai Jiangshan
2010-06-07T08:42:44Z

Avi Kivity wrote:
> The kvm mmu synchronizes shadow ptes using the mmu lock, however the cpu
> will happily ignore the lock when setting the accessed bit. This can cause
> the accessed bit to be lost. Luckily this only results in incorrect page
> selection for swap.
>

Atomic operation is heavy and slow, it hurts performance.
Incorrect page selection for swap also hurts performance.

I think there are very rare competitions happened and cause
the accessed bit to be lost. Since there is no incorrect result
when the accessed bit is lost. Is this problem over concern?

Lai