Messages in this thread | | | Date | Mon, 7 Jan 2008 19:08:22 -0800 | From | Andrew Morton <> | Subject | Re: free_pages_check |
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On Mon, 7 Jan 2008 18:43:46 -0800 "Yinghai Lu" <yhlu.kernel@gmail.com> wrote:
> wonder why free_pages_check mm/page_alloc.c is using bit OR than logical OR > > @@ -450,9 +450,9 @@ static inline void __free_one_page(struc > > static inline int free_pages_check(struct page *page) > { > - if (unlikely(page_mapcount(page) | > - (page->mapping != NULL) | > - (page_count(page) != 0) | > + if (unlikely(page_mapcount(page) || > + (page->mapping != NULL) || > + (page_count(page) != 0) || > (page->flags & ( > 1 << PG_lru | > 1 << PG_private |
It's a hack^Wtrick to avoid the generation of a series of not-taken branches. I don't recall anyone verifying that it is actually of any benefit, but the theory is good.
The lack of a comment, however, is not.
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