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Date: Wed, 26 Jun 2019 21:10:00 +0800 From: Pingfan Liu <kernelfans@...il.com> To: Linux-mm@...ck.org Cc: Pingfan Liu <kernelfans@...il.com>, Andrew Morton <akpm@...ux-foundation.org>, Ira Weiny <ira.weiny@...el.com>, Mike Rapoport <rppt@...ux.ibm.com>, "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>, Thomas Gleixner <tglx@...utronix.de>, John Hubbard <jhubbard@...dia.com>, "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>, Christoph Hellwig <hch@....de>, Keith Busch <keith.busch@...el.com>, Mike Kravetz <mike.kravetz@...cle.com>, Linux-kernel@...r.kernel.org Subject: [PATCHv4] mm/gup: speed up check_and_migrate_cma_pages() on huge page Both hugetlb and thp locate on the same migration type of pageblock, since they are allocated from a free_list[]. Based on this fact, it is enough to check on a single subpage to decide the migration type of the whole huge page. By this way, it saves (2M/4K - 1) times loop for pmd_huge on x86, similar on other archs. Furthermore, when executing isolate_huge_page(), it avoid taking global hugetlb_lock many times, and meanless remove/add to the local link list cma_page_list. Signed-off-by: Pingfan Liu <kernelfans@...il.com> Cc: Andrew Morton <akpm@...ux-foundation.org> Cc: Ira Weiny <ira.weiny@...el.com> Cc: Mike Rapoport <rppt@...ux.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com> Cc: Thomas Gleixner <tglx@...utronix.de> Cc: John Hubbard <jhubbard@...dia.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com> Cc: Christoph Hellwig <hch@....de> Cc: Keith Busch <keith.busch@...el.com> Cc: Mike Kravetz <mike.kravetz@...cle.com> Cc: Linux-kernel@...r.kernel.org --- v3 -> v4: fix C language precedence issue mm/gup.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index ddde097..ffca55b 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1342,19 +1342,22 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk, LIST_HEAD(cma_page_list); check_again: - for (i = 0; i < nr_pages; i++) { + for (i = 0; i < nr_pages;) { + + struct page *head = compound_head(pages[i]); + long step = 1; + + if (PageCompound(head)) + step = (1 << compound_order(head)) - (pages[i] - head); /* * If we get a page from the CMA zone, since we are going to * be pinning these entries, we might as well move them out * of the CMA zone if possible. */ - if (is_migrate_cma_page(pages[i])) { - - struct page *head = compound_head(pages[i]); - - if (PageHuge(head)) { + if (is_migrate_cma_page(head)) { + if (PageHuge(head)) isolate_huge_page(head, &cma_page_list); - } else { + else { if (!PageLRU(head) && drain_allow) { lru_add_drain_all(); drain_allow = false; @@ -1369,6 +1372,8 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk, } } } + + i += step; } if (!list_empty(&cma_page_list)) { -- 2.7.5
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