| Message ID | 1561112116-23072-1-git-send-email-kernelfans@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/gup: speed up check_and_migrate_cma_pages() on huge page | expand |
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 <kernelfans@gmail.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Ira Weiny <ira.weiny@intel.com> > Cc: Mike Rapoport <rppt@linux.ibm.com> > Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: John Hubbard <jhubbard@nvidia.com> > Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> > Cc: Christoph Hellwig <hch@lst.de> > Cc: Keith Busch <keith.busch@intel.com> > Cc: Mike Kravetz <mike.kravetz@oracle.com> > Cc: Linux-kernel@vger.kernel.org > --- > 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 <ira.weiny@intel.com> 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 <kernelfans@gmail.com> > > Cc: Andrew Morton <akpm@linux-foundation.org> > > Cc: Ira Weiny <ira.weiny@intel.com> > > Cc: Mike Rapoport <rppt@linux.ibm.com> > > Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> > > Cc: Thomas Gleixner <tglx@linutronix.de> > > Cc: John Hubbard <jhubbard@nvidia.com> > > Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> > > Cc: Christoph Hellwig <hch@lst.de> > > Cc: Keith Busch <keith.busch@intel.com> > > Cc: Mike Kravetz <mike.kravetz@oracle.com> > > Cc: Linux-kernel@vger.kernel.org > > --- > > 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 > >
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)) {
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@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: John Hubbard <jhubbard@nvidia.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Keith Busch <keith.busch@intel.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Linux-kernel@vger.kernel.org --- mm/gup.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)