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Message-Id: <1561349561-8302-1-git-send-email-kernelfans@gmail.com>
Date: Mon, 24 Jun 2019 12:12:41 +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: [PATCHv2] 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
---
mm/gup.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index ddde097..544f5de 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 = 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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