Re: [PATCHv2] mm/gup: speed up check_and_migrate_cma_pages() on huge page
On Mon, Jun 24, 2019 at 01:34:01PM +0800, Pingfan Liu wrote:
> On Mon, Jun 24, 2019 at 1:32 PM Pingfan Liu wrote:
> >
> > On Mon, Jun 24, 2019 at 12:43 PM Ira Weiny wrote:
> > >
> > > On Mon, Jun 24, 2019 at 12:12:41PM +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
> > > > Cc: Andrew Morton
> > > > Cc: Ira Weiny
> > > > Cc: Mike Rapoport
> > > > Cc: "Kirill A. Shutemov"
> > > > Cc: Thomas Gleixner
> > > > Cc: John Hubbard
> > > > Cc: "Aneesh Kumar K.V"
> > > > Cc: Christoph Hellwig
> > > > Cc: Keith Busch
> > > > Cc: Mike Kravetz
> > > > Cc: Linux-kernel@vger.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);
> > >
> > > Sorry if I missed this last time. compound_order() is not correct here.
> > For thp, prep_transhuge_page()->prep_compound_page()->set_compound_order().
> > For smaller hugetlb,
> > prep_new_huge_page()->prep_compound_page()->set_compound_order().
> > For gigantic page, prep_compound_gigantic_page()->set_compound_order().
> >
> > Do I miss anything?
> >
> Oh, got it. It should be 1< > Thanks,
> > Pingfan
> > [...]
Re: [PATCHv2] mm/gup: speed up check_and_migrate_cma_pages() on huge page
On Mon, Jun 24, 2019 at 1:32 PM Pingfan Liu wrote:
>
> On Mon, Jun 24, 2019 at 12:43 PM Ira Weiny wrote:
> >
> > On Mon, Jun 24, 2019 at 12:12:41PM +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
> > > Cc: Andrew Morton
> > > Cc: Ira Weiny
> > > Cc: Mike Rapoport
> > > Cc: "Kirill A. Shutemov"
> > > Cc: Thomas Gleixner
> > > Cc: John Hubbard
> > > Cc: "Aneesh Kumar K.V"
> > > Cc: Christoph Hellwig
> > > Cc: Keith Busch
> > > Cc: Mike Kravetz
> > > Cc: Linux-kernel@vger.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);
> >
> > Sorry if I missed this last time. compound_order() is not correct here.
> For thp, prep_transhuge_page()->prep_compound_page()->set_compound_order().
> For smaller hugetlb,
> prep_new_huge_page()->prep_compound_page()->set_compound_order().
> For gigantic page, prep_compound_gigantic_page()->set_compound_order().
>
> Do I miss anything?
>
Oh, got it. It should be 1< Thanks,
> Pingfan
> [...]
Re: [PATCHv2] mm/gup: speed up check_and_migrate_cma_pages() on huge page
On Mon, Jun 24, 2019 at 12:43 PM Ira Weiny wrote:
>
> On Mon, Jun 24, 2019 at 12:12:41PM +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
> > Cc: Andrew Morton
> > Cc: Ira Weiny
> > Cc: Mike Rapoport
> > Cc: "Kirill A. Shutemov"
> > Cc: Thomas Gleixner
> > Cc: John Hubbard
> > Cc: "Aneesh Kumar K.V"
> > Cc: Christoph Hellwig
> > Cc: Keith Busch
> > Cc: Mike Kravetz
> > Cc: Linux-kernel@vger.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);
>
> Sorry if I missed this last time. compound_order() is not correct here.
For thp, prep_transhuge_page()->prep_compound_page()->set_compound_order().
For smaller hugetlb,
prep_new_huge_page()->prep_compound_page()->set_compound_order().
For gigantic page, prep_compound_gigantic_page()->set_compound_order().
Do I miss anything?
Thanks,
Pingfan
[...]
Re: [PATCHv2] mm/gup: speed up check_and_migrate_cma_pages() on huge page
On Mon, Jun 24, 2019 at 12:12:41PM +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
> Cc: Andrew Morton
> Cc: Ira Weiny
> Cc: Mike Rapoport
> Cc: "Kirill A. Shutemov"
> Cc: Thomas Gleixner
> Cc: John Hubbard
> Cc: "Aneesh Kumar K.V"
> Cc: Christoph Hellwig
> Cc: Keith Busch
> Cc: Mike Kravetz
> Cc: Linux-kernel@vger.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);
Sorry if I missed this last time. compound_order() is not correct here.
Ira
> /*
>* 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, _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(_page_list)) {
> --
> 2.7.5
>
