On Tue, 18 Oct 2016 16:04:06 -0700 (PDT) David Rientjes <rientjes@xxxxxxxxxx> wrote: > While doing MADV_DONTNEED on a large area of thp memory, I noticed we > encountered many unlikely() branches in profiles for each backing > hugepage. This is because zap_pmd_range() would call split_huge_pmd(), > which rechecked the conditions that were already validated, but as part of > an unlikely() branch. > > Avoid the unlikely() branch when in a context where pmd is known to be > good for __split_huge_pmd() directly. Before: text data bss dec hex filename 38442 75 48 38565 96a5 mm/memory.o 21755 2369 18464 42588 a65c mm/mempolicy.o 4557 1816 0 6373 18e5 mm/mprotect.o After: 38362 75 48 38485 9655 mm/memory.o 21714 2369 18464 42547 a633 mm/mempolicy.o 4541 1816 0 6357 18d5 mm/mprotect.o So there's a size improvment too. gcc-4.4.4. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>