On Fri, Apr 12, 2024 at 11:41 AM David Matlack <dmatlack@xxxxxxxxxx> wrote: > > 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? I don't have these results right now. For the next version I will (1) separate the series into the locking change and the bitmap change, and I will (2) have performance data for each change separately. It is conceivable that the bitmap change should just be considered as a completely separate patchset.
