Re: [PATCH v3 0/7] mm/kvm: Improve parallelism for access bit harvesting

David Matlack
2024-04-12T18:41:17Z

On 2024-04-01 11:29 PM, James Houghton wrote:
> This patchset adds a fast path in KVM to test and clear access bits on
> sptes without taking the mmu_lock. It also adds support for using a
> bitmap to (1) test the access bits for many sptes in a single call to
> mmu_notifier_test_young, and to (2) clear the access bits for many ptes
> in a single call to mmu_notifier_clear_young.

How much improvement would we get if we _just_ made test/clear_young
lockless on x86 and hold the read-lock on arm64? And then how much
benefit does the bitmap look-around add on top of that?