Re: [PATCH 0/2] Optimize mmu_notifier->invalidate_range callback

On Mon, 16 Oct 2017 23:10:01 -0400
jglisse@redhat.com wrote:

From: J=C3=A9r=C3=B4me Glisse <redacted>
=20
(Andrew you already have v1 in your queue of patch 1, patch 2 is new,
 i think you can drop it patch 1 v1 for v2, v2 is bit more conservative
 and i fixed typos)
=20
All this only affect user of invalidate_range callback (at this time
CAPI arch/powerpc/platforms/powernv/npu-dma.c, IOMMU ATS/PASID in
drivers/iommu/amd_iommu_v2.c|intel-svm.c)
=20
This patchset remove useless double call to mmu_notifier->invalidate_range
callback wherever it is safe to do so. The first patch just remove useless
call

As in an extra call? Where does that come from?

and add documentation explaining why it is safe to do so. The second
patch go further by introducing mmu_notifier_invalidate_range_only_end()
which skip callback to invalidate_range this can be done when clearing a
pte, pmd or pud with notification which call invalidate_range right after
clearing under the page table lock.

Balbir Singh.