From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757077Ab3JIR3E (ORCPT ); Wed, 9 Oct 2013 13:29:04 -0400 Received: from terminus.zytor.com ([198.137.202.10]:56175 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932146Ab3JIR3A (ORCPT ); Wed, 9 Oct 2013 13:29:00 -0400 Date: Wed, 9 Oct 2013 10:28:22 -0700 From: tip-bot for Mel Gorman Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, peterz@infradead.org, hannes@cmpxchg.org, riel@redhat.com, aarcange@redhat.com, srikar@linux.vnet.ibm.com, mgorman@suse.de, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, peterz@infradead.org, hannes@cmpxchg.org, riel@redhat.com, aarcange@redhat.com, srikar@linux.vnet.ibm.com, mgorman@suse.de, tglx@linutronix.de In-Reply-To: <1381141781-10992-28-git-send-email-mgorman@suse.de> References: <1381141781-10992-28-git-send-email-mgorman@suse.de> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] mm: numa: Scan pages with elevated page_mapcount Git-Commit-ID: 1bc115d87dffd1c43bdc3c9c9d1e3a51c195d18e X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (terminus.zytor.com [127.0.0.1]); Wed, 09 Oct 2013 10:28:29 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 1bc115d87dffd1c43bdc3c9c9d1e3a51c195d18e Gitweb: http://git.kernel.org/tip/1bc115d87dffd1c43bdc3c9c9d1e3a51c195d18e Author: Mel Gorman AuthorDate: Mon, 7 Oct 2013 11:29:05 +0100 Committer: Ingo Molnar CommitDate: Wed, 9 Oct 2013 12:40:32 +0200 mm: numa: Scan pages with elevated page_mapcount Currently automatic NUMA balancing is unable to distinguish between false shared versus private pages except by ignoring pages with an elevated page_mapcount entirely. This avoids shared pages bouncing between the nodes whose task is using them but that is ignored quite a lot of data. This patch kicks away the training wheels in preparation for adding support for identifying shared/private pages is now in place. The ordering is so that the impact of the shared/private detection can be easily measured. Note that the patch does not migrate shared, file-backed within vmas marked VM_EXEC as these are generally shared library pages. Migrating such pages is not beneficial as there is an expectation they are read-shared between caches and iTLB and iCache pressure is generally low. Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel Cc: Andrea Arcangeli Cc: Johannes Weiner Cc: Srikar Dronamraju Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1381141781-10992-28-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar --- include/linux/migrate.h | 7 ++++--- mm/huge_memory.c | 12 +++++------- mm/memory.c | 7 ++----- mm/migrate.c | 17 ++++++----------- mm/mprotect.c | 4 +--- 5 files changed, 18 insertions(+), 29 deletions(-) diff --git a/include/linux/migrate.h b/include/linux/migrate.h index 8d3c57f..f5096b5 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -90,11 +90,12 @@ static inline int migrate_huge_page_move_mapping(struct address_space *mapping, #endif /* CONFIG_MIGRATION */ #ifdef CONFIG_NUMA_BALANCING -extern int migrate_misplaced_page(struct page *page, int node); -extern int migrate_misplaced_page(struct page *page, int node); +extern int migrate_misplaced_page(struct page *page, + struct vm_area_struct *vma, int node); extern bool migrate_ratelimited(int node); #else -static inline int migrate_misplaced_page(struct page *page, int node) +static inline int migrate_misplaced_page(struct page *page, + struct vm_area_struct *vma, int node) { return -EAGAIN; /* can't migrate now */ } diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 9142167..2a28c2c 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1484,14 +1484,12 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, struct page *page = pmd_page(*pmd); /* - * Only check non-shared pages. Do not trap faults - * against the zero page. The read-only data is likely - * to be read-cached on the local CPU cache and it is - * less useful to know about local vs remote hits on - * the zero page. + * Do not trap faults against the zero page. The + * read-only data is likely to be read-cached on the + * local CPU cache and it is less useful to know about + * local vs remote hits on the zero page. */ - if (page_mapcount(page) == 1 && - !is_huge_zero_page(page) && + if (!is_huge_zero_page(page) && !pmd_numa(*pmd)) { entry = pmdp_get_and_clear(mm, addr, pmd); entry = pmd_mknuma(entry); diff --git a/mm/memory.c b/mm/memory.c index 24bc9b8..3e3b4b8 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3577,7 +3577,7 @@ int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, } /* Migrate to the requested node */ - migrated = migrate_misplaced_page(page, target_nid); + migrated = migrate_misplaced_page(page, vma, target_nid); if (migrated) page_nid = target_nid; @@ -3642,16 +3642,13 @@ static int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, page = vm_normal_page(vma, addr, pteval); if (unlikely(!page)) continue; - /* only check non-shared pages */ - if (unlikely(page_mapcount(page) != 1)) - continue; last_nid = page_nid_last(page); page_nid = page_to_nid(page); target_nid = numa_migrate_prep(page, vma, addr, page_nid); pte_unmap_unlock(pte, ptl); if (target_nid != -1) { - migrated = migrate_misplaced_page(page, target_nid); + migrated = migrate_misplaced_page(page, vma, target_nid); if (migrated) page_nid = target_nid; } else { diff --git a/mm/migrate.c b/mm/migrate.c index 7bd90d3..fcba2f4 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1599,7 +1599,8 @@ int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page) * node. Caller is expected to have an elevated reference count on * the page that will be dropped by this function before returning. */ -int migrate_misplaced_page(struct page *page, int node) +int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma, + int node) { pg_data_t *pgdat = NODE_DATA(node); int isolated; @@ -1607,10 +1608,11 @@ int migrate_misplaced_page(struct page *page, int node) LIST_HEAD(migratepages); /* - * Don't migrate pages that are mapped in multiple processes. - * TODO: Handle false sharing detection instead of this hammer + * Don't migrate file pages that are mapped in multiple processes + * with execute permissions as they are probably shared libraries. */ - if (page_mapcount(page) != 1) + if (page_mapcount(page) != 1 && page_is_file_cache(page) && + (vma->vm_flags & VM_EXEC)) goto out; /* @@ -1661,13 +1663,6 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm, int page_lru = page_is_file_cache(page); /* - * Don't migrate pages that are mapped in multiple processes. - * TODO: Handle false sharing detection instead of this hammer - */ - if (page_mapcount(page) != 1) - goto out_dropref; - - /* * Rate-limit the amount of data that is being migrated to a node. * Optimal placement is no good if the memory bus is saturated and * all the time is being spent migrating! diff --git a/mm/mprotect.c b/mm/mprotect.c index 2da33dc..41e0292 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -69,9 +69,7 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, if (last_nid != this_nid) all_same_node = false; - /* only check non-shared pages */ - if (!pte_numa(oldpte) && - page_mapcount(page) == 1) { + if (!pte_numa(oldpte)) { ptent = pte_mknuma(ptent); updated = true; }