From: "Huang, Ying" <ying.huang@intel.com> To: Andrew Morton <akpm@linux-foundation.org> Cc: tim.c.chen@intel.com, dave.hansen@intel.com, andi.kleen@intel.com, aaron.lu@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Huang Ying <ying.huang@intel.com>, Andrea Arcangeli <aarcange@redhat.com>, "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>, Ebru Akagunduz <ebru.akagunduz@gmail.com> Subject: [PATCH -v4 RESEND 7/9] mm, THP: Add can_split_huge_page() Date: Fri, 28 Oct 2016 13:56:06 +0800 [thread overview] Message-ID: <20161028055608.1736-8-ying.huang@intel.com> (raw) In-Reply-To: <20161028055608.1736-1-ying.huang@intel.com> From: Huang Ying <ying.huang@intel.com> Separates checking whether we can split the huge page from split_huge_page_to_list() into a function. This will help to check that before splitting the THP (Transparent Huge Page) really. This will be used for delaying splitting THP during swapping out. Where for a THP, we will allocate a swap cluster, add the THP into the swap cache, then split the THP. To avoid the unnecessary operations for the un-splittable THP, we will check that firstly. There is no functionality change in this patch. Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> --- include/linux/huge_mm.h | 7 +++++++ mm/huge_memory.c | 13 ++++++++++++- 2 files changed, 19 insertions(+), 1 deletion(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 9b9f65d..14ffa3f 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -94,6 +94,7 @@ extern unsigned long thp_get_unmapped_area(struct file *filp, extern void prep_transhuge_page(struct page *page); extern void free_transhuge_page(struct page *page); +bool can_split_huge_page(struct page *page); int split_huge_page_to_list(struct page *page, struct list_head *list); static inline int split_huge_page(struct page *page) { @@ -176,6 +177,12 @@ static inline void prep_transhuge_page(struct page *page) {} #define thp_get_unmapped_area NULL +static inline bool +can_split_huge_page(struct page *page) +{ + BUILD_BUG(); + return false; +} static inline int split_huge_page_to_list(struct page *page, struct list_head *list) { diff --git a/mm/huge_memory.c b/mm/huge_memory.c index cdcd25c..326b145 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2013,6 +2013,17 @@ int page_trans_huge_mapcount(struct page *page, int *total_mapcount) return ret; } +/* Racy check whether the huge page can be split */ +bool can_split_huge_page(struct page *page) +{ + int extra_pins = 0; + + /* Additional pins from radix tree */ + if (!PageAnon(page)) + extra_pins = HPAGE_PMD_NR; + return total_mapcount(page) == page_count(page) - extra_pins - 1; +} + /* * This function splits huge page into normal pages. @page can point to any * subpage of huge page to split. Split doesn't change the position of @page. @@ -2083,7 +2094,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) * Racy check if we can split the page, before freeze_page() will * split PMDs */ - if (total_mapcount(head) != page_count(head) - extra_pins - 1) { + if (!can_split_huge_page(head)) { ret = -EBUSY; goto out_unlock; } -- 2.9.3
WARNING: multiple messages have this Message-ID (diff)
From: "Huang, Ying" <ying.huang@intel.com> To: Andrew Morton <akpm@linux-foundation.org> Cc: tim.c.chen@intel.com, dave.hansen@intel.com, andi.kleen@intel.com, aaron.lu@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Huang Ying <ying.huang@intel.com>, Andrea Arcangeli <aarcange@redhat.com>, "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>, Ebru Akagunduz <ebru.akagunduz@gmail.com> Subject: [PATCH -v4 RESEND 7/9] mm, THP: Add can_split_huge_page() Date: Fri, 28 Oct 2016 13:56:06 +0800 [thread overview] Message-ID: <20161028055608.1736-8-ying.huang@intel.com> (raw) In-Reply-To: <20161028055608.1736-1-ying.huang@intel.com> From: Huang Ying <ying.huang@intel.com> Separates checking whether we can split the huge page from split_huge_page_to_list() into a function. This will help to check that before splitting the THP (Transparent Huge Page) really. This will be used for delaying splitting THP during swapping out. Where for a THP, we will allocate a swap cluster, add the THP into the swap cache, then split the THP. To avoid the unnecessary operations for the un-splittable THP, we will check that firstly. There is no functionality change in this patch. Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> --- include/linux/huge_mm.h | 7 +++++++ mm/huge_memory.c | 13 ++++++++++++- 2 files changed, 19 insertions(+), 1 deletion(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 9b9f65d..14ffa3f 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -94,6 +94,7 @@ extern unsigned long thp_get_unmapped_area(struct file *filp, extern void prep_transhuge_page(struct page *page); extern void free_transhuge_page(struct page *page); +bool can_split_huge_page(struct page *page); int split_huge_page_to_list(struct page *page, struct list_head *list); static inline int split_huge_page(struct page *page) { @@ -176,6 +177,12 @@ static inline void prep_transhuge_page(struct page *page) {} #define thp_get_unmapped_area NULL +static inline bool +can_split_huge_page(struct page *page) +{ + BUILD_BUG(); + return false; +} static inline int split_huge_page_to_list(struct page *page, struct list_head *list) { diff --git a/mm/huge_memory.c b/mm/huge_memory.c index cdcd25c..326b145 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2013,6 +2013,17 @@ int page_trans_huge_mapcount(struct page *page, int *total_mapcount) return ret; } +/* Racy check whether the huge page can be split */ +bool can_split_huge_page(struct page *page) +{ + int extra_pins = 0; + + /* Additional pins from radix tree */ + if (!PageAnon(page)) + extra_pins = HPAGE_PMD_NR; + return total_mapcount(page) == page_count(page) - extra_pins - 1; +} + /* * This function splits huge page into normal pages. @page can point to any * subpage of huge page to split. Split doesn't change the position of @page. @@ -2083,7 +2094,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) * Racy check if we can split the page, before freeze_page() will * split PMDs */ - if (total_mapcount(head) != page_count(head) - extra_pins - 1) { + if (!can_split_huge_page(head)) { ret = -EBUSY; goto out_unlock; } -- 2.9.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2016-10-28 5:56 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-10-28 5:55 [PATCH -v4 RESEND 0/9] THP swap: Delay splitting THP during swapping out Huang, Ying 2016-10-28 5:55 ` Huang, Ying 2016-10-28 5:56 ` [PATCH -v4 RESEND 1/9] mm, swap: Make swap cluster size same of THP size on x86_64 Huang, Ying 2016-10-28 5:56 ` Huang, Ying 2016-10-28 5:56 ` [PATCH -v4 RESEND 2/9] mm, memcg: Support to charge/uncharge multiple swap entries Huang, Ying 2016-10-28 5:56 ` Huang, Ying 2016-10-28 5:56 ` [PATCH -v4 RESEND 3/9] mm, THP, swap: Add swap cluster allocate/free functions Huang, Ying 2016-10-28 5:56 ` Huang, Ying 2016-10-28 5:56 ` [PATCH -v4 RESEND 4/9] mm, THP, swap: Add get_huge_swap_page() Huang, Ying 2016-10-28 5:56 ` Huang, Ying 2016-10-28 5:56 ` [PATCH -v4 RESEND 5/9] mm, THP, swap: Support to clear SWAP_HAS_CACHE for huge page Huang, Ying 2016-10-28 5:56 ` Huang, Ying 2016-10-28 5:56 ` [PATCH -v4 RESEND 6/9] mm, THP, swap: Support to add/delete THP to/from swap cache Huang, Ying 2016-10-28 5:56 ` Huang, Ying 2016-10-28 8:08 ` Hillf Danton 2016-10-28 8:08 ` Hillf Danton 2016-10-28 8:30 ` Huang, Ying 2016-10-28 8:30 ` Huang, Ying 2016-10-28 5:56 ` Huang, Ying [this message] 2016-10-28 5:56 ` [PATCH -v4 RESEND 7/9] mm, THP: Add can_split_huge_page() Huang, Ying 2016-10-28 5:56 ` [PATCH -v4 RESEND 8/9] mm, THP, swap: Support to split THP in swap cache Huang, Ying 2016-10-28 5:56 ` Huang, Ying 2016-10-28 10:18 ` Hillf Danton 2016-10-28 10:18 ` Hillf Danton 2016-10-31 1:26 ` Huang, Ying 2016-10-31 1:26 ` Huang, Ying 2016-10-28 5:56 ` [PATCH -v4 RESEND 9/9] mm, THP, swap: Delay splitting THP during swap out Huang, Ying 2016-10-28 5:56 ` Huang, Ying
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