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 <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Ira Weiny <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: "Aneesh Kumar K.V" <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Keith Busch <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: [email protected]
---
mm/gup.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index ddde097..2eecb16 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1342,16 +1342,19 @@ 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)) {
isolate_huge_page(head, &cma_page_list);
} else {
@@ -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
On Fri, Jun 21, 2019 at 06:15:16PM +0800, Pingfan Liu wrote:
> 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 <[email protected]>
> Cc: Andrew Morton <[email protected]>
> Cc: Ira Weiny <[email protected]>
> Cc: Mike Rapoport <[email protected]>
> Cc: "Kirill A. Shutemov" <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: John Hubbard <[email protected]>
> Cc: "Aneesh Kumar K.V" <[email protected]>
> Cc: Christoph Hellwig <[email protected]>
> Cc: Keith Busch <[email protected]>
> Cc: Mike Kravetz <[email protected]>
> Cc: [email protected]
> ---
> mm/gup.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/mm/gup.c b/mm/gup.c
> index ddde097..2eecb16 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -1342,16 +1342,19 @@ 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])) {
I like this but I think for consistency I would change this pages[i] to be
head. Even though it is not required.
Ira
> -
> - struct page *head = compound_head(pages[i]);
> -
> if (PageHuge(head)) {
> isolate_huge_page(head, &cma_page_list);
> } else {
> @@ -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
>
On Sat, Jun 22, 2019 at 2:13 AM Ira Weiny <[email protected]> wrote:
>
> On Fri, Jun 21, 2019 at 06:15:16PM +0800, Pingfan Liu wrote:
> > 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 <[email protected]>
> > Cc: Andrew Morton <[email protected]>
> > Cc: Ira Weiny <[email protected]>
> > Cc: Mike Rapoport <[email protected]>
> > Cc: "Kirill A. Shutemov" <[email protected]>
> > Cc: Thomas Gleixner <[email protected]>
> > Cc: John Hubbard <[email protected]>
> > Cc: "Aneesh Kumar K.V" <[email protected]>
> > Cc: Christoph Hellwig <[email protected]>
> > Cc: Keith Busch <[email protected]>
> > Cc: Mike Kravetz <[email protected]>
> > Cc: [email protected]
> > ---
> > mm/gup.c | 13 +++++++++----
> > 1 file changed, 9 insertions(+), 4 deletions(-)
> >
> > diff --git a/mm/gup.c b/mm/gup.c
> > index ddde097..2eecb16 100644
> > --- a/mm/gup.c
> > +++ b/mm/gup.c
> > @@ -1342,16 +1342,19 @@ 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])) {
>
> I like this but I think for consistency I would change this pages[i] to be
> head. Even though it is not required.
Yes, agree. Thank you for your good suggestion.
Regards,
Pingfan
>
> Ira
>
> > -
> > - struct page *head = compound_head(pages[i]);
> > -
> > if (PageHuge(head)) {
> > isolate_huge_page(head, &cma_page_list);
> > } else {
> > @@ -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
> >