Re: [PATCH v1] mm/contpte: Optimize loop to reduce redundant operations

Lance Yang
2025-04-07T11:33:00Z

Thanks for the patch. Would the following change be better?

diff --git a/arch/arm64/mm/contpte.c b/arch/arm64/mm/contpte.c
index 55107d27d3f8..64eb3b2fbf06 100644
--- a/arch/arm64/mm/contpte.c
+++ b/arch/arm64/mm/contpte.c
@@ -174,6 +174,9 @@ pte_t contpte_ptep_get(pte_t *ptep, pte_t orig_pte)

if (pte_young(pte))
orig_pte = pte_mkyoung(orig_pte);
+
+ if (pte_young(orig_pte) && pte_dirty(orig_pte))
+ break;
}

return orig_pte;
--

We can check the orig_pte flags directly instead of using extra boolean
variables, which gives us an early-exit when both dirty and young flags
are set.

Also, is this optimization really needed for the common case?

Thanks,
Lance