Messages in this thread | | | Date | Mon, 16 Jun 2014 23:49:34 +0300 | From | "Kirill A. Shutemov" <> | Subject | Re: [PATCH] mm, thp: move invariant bug check out of loop in __split_huge_page_map |
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On Mon, Jun 16, 2014 at 03:35:48PM -0400, Waiman Long wrote: > In the __split_huge_page_map() function, the check for > page_mapcount(page) is invariant within the for loop. Because of the > fact that the macro is implemented using atomic_read(), the redundant > check cannot be optimized away by the compiler leading to unnecessary > read to the page structure. > > This patch move the invariant bug check out of the loop so that it > will be done only once.
Looks okay, but why? Was you able to measure difference?
-- Kirill A. Shutemov
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