Messages in this thread |  | | From | Pingfan Liu <> | Date | Mon, 24 Jun 2019 13:34:01 +0800 | Subject | Re: [PATCHv2] mm/gup: speed up check_and_migrate_cma_pages() on huge page |
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On Mon, Jun 24, 2019 at 1:32 PM Pingfan Liu <kernelfans@gmail.com> wrote: > > On Mon, Jun 24, 2019 at 12:43 PM Ira Weiny <ira.weiny@intel.com> 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 <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 | 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<<compound_order(head) > Thanks, > Pingfan > [...]
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