Messages in this thread | | | Date | Thu, 22 Sep 2022 14:03:55 +0800 | Subject | Re: [RFC 1/6] mm/migrate_pages: separate huge page and normal pages migration | From | Baolin Wang <> |
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On 9/21/2022 2:06 PM, Huang Ying wrote: > This is a preparation patch to batch the page unmapping and moving for > the normal pages and THPs. Based on that we can batch the TLB > shootdown during the page migration and make it possible to use some > hardware accelerator for the page copying. > > In this patch the huge page (PageHuge()) and normal page and THP > migration is separated in migrate_pages() to make it easy to change > the normal page and THP migration implementation. > > Signed-off-by: "Huang, Ying" <ying.huang@intel.com> > Cc: Zi Yan <ziy@nvidia.com> > Cc: Yang Shi <shy828301@gmail.com> > Cc: Baolin Wang <baolin.wang@linux.alibaba.com> > Cc: Oscar Salvador <osalvador@suse.de> > Cc: Matthew Wilcox <willy@infradead.org> > --- > mm/migrate.c | 73 +++++++++++++++++++++++++++++++++++++++++++++------- > 1 file changed, 64 insertions(+), 9 deletions(-) > > diff --git a/mm/migrate.c b/mm/migrate.c > index 571d8c9fd5bc..117134f1c6dc 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -1414,6 +1414,66 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, > > trace_mm_migrate_pages_start(mode, reason); > > + for (pass = 0; pass < 10 && retry; pass++) { > + retry = 0; > + > + list_for_each_entry_safe(page, page2, from, lru) { > + nr_subpages = compound_nr(page); > + cond_resched(); > + > + if (!PageHuge(page)) > + continue; > + > + rc = unmap_and_move_huge_page(get_new_page, > + put_new_page, private, page, > + pass > 2, mode, reason, > + &ret_pages); > + /* > + * The rules are: > + * Success: hugetlb page will be put back > + * -EAGAIN: stay on the from list > + * -ENOMEM: stay on the from list > + * -ENOSYS: stay on the from list > + * Other errno: put on ret_pages list then splice to > + * from list > + */ > + switch(rc) { > + case -ENOSYS: > + /* Hugetlb migration is unsupported */ > + nr_failed++; > + nr_failed_pages += nr_subpages; > + list_move_tail(&page->lru, &ret_pages); > + break; > + case -ENOMEM: > + /* > + * When memory is low, don't bother to try to migrate > + * other pages, just exit. > + */ > + nr_failed++; > + nr_failed_pages += nr_subpages + nr_retry_pages; > + goto out; > + case -EAGAIN: > + retry++; > + nr_retry_pages += nr_subpages; > + break; > + case MIGRATEPAGE_SUCCESS: > + nr_succeeded += nr_subpages; > + break; > + default: > + /* > + * Permanent failure (-EBUSY, etc.): > + * unlike -EAGAIN case, the failed page is > + * removed from migration page list and not > + * retried in the next outer loop. > + */ > + nr_failed++; > + nr_failed_pages += nr_subpages; > + break; > + } > + } > + } > + nr_failed += retry;
Seems we should also record the nr_retry_pages? since the second loop will reset the nr_retry_pages.
nr_failed_pages += nr_retry_pages;
Besides, I also agree with Zi Yan's comment to simplify this larger function.
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