From: Mel Gorman <mgorman@suse.de>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Andrea Arcangeli <aarcange@redhat.com>,
Ingo Molnar <mingo@kernel.org>
Cc: Rik van Riel <riel@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Hugh Dickins <hughd@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>, Mel Gorman <mgorman@suse.de>
Subject: [PATCH 06/19] mm: numa: teach gup_fast about pmd_numa
Date: Tue, 6 Nov 2012 09:14:42 +0000 [thread overview]
Message-ID: <1352193295-26815-7-git-send-email-mgorman@suse.de> (raw)
In-Reply-To: <1352193295-26815-1-git-send-email-mgorman@suse.de>
From: Andrea Arcangeli <aarcange@redhat.com>
When scanning pmds, the pmd may be of numa type (_PAGE_PRESENT not set),
however the pte might be present. Therefore, gup_pmd_range() must return
0 in this case to avoid losing a NUMA hinting page fault during gup_fast.
Note: gup_fast will skip over non present ptes (like numa types), so
no explicit check is needed for the pte_numa case. gup_fast will also
skip over THP when the trans huge pmd is non present. So, the pmd_numa
case will also be correctly skipped with no additional code changes
required.
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
arch/x86/mm/gup.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
index dd74e46..02c5ec5 100644
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -163,8 +163,19 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
* can't because it has irq disabled and
* wait_split_huge_page() would never return as the
* tlb flush IPI wouldn't run.
+ *
+ * The pmd_numa() check is needed because the code
+ * doesn't check the _PAGE_PRESENT bit of the pmd if
+ * the gup_pte_range() path is taken. NOTE: not all
+ * gup_fast users will will access the page contents
+ * using the CPU through the NUMA memory channels like
+ * KVM does. So we're forced to trigger NUMA hinting
+ * page faults unconditionally for all gup_fast users
+ * even though NUMA hinting page faults aren't useful
+ * to I/O drivers that will access the page with DMA
+ * and not with the CPU.
*/
- if (pmd_none(pmd) || pmd_trans_splitting(pmd))
+ if (pmd_none(pmd) || pmd_trans_splitting(pmd) || pmd_numa(pmd))
return 0;
if (unlikely(pmd_large(pmd))) {
if (!gup_huge_pmd(pmd, addr, next, write, pages, nr))
--
1.7.9.2
--
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next prev parent reply other threads:[~2012-11-06 9:15 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-06 9:14 [RFC PATCH 00/19] Foundation for automatic NUMA balancing Mel Gorman
2012-11-06 9:14 ` [PATCH 01/19] mm: compaction: Move migration fail/success stats to migrate.c Mel Gorman
2012-11-06 17:32 ` Rik van Riel
2012-11-06 9:14 ` [PATCH 02/19] mm: migrate: Add a tracepoint for migrate_pages Mel Gorman
2012-11-06 17:33 ` Rik van Riel
2012-11-06 9:14 ` [PATCH 03/19] mm: compaction: Add scanned and isolated counters for compaction Mel Gorman
2012-11-06 17:35 ` Rik van Riel
2012-11-06 9:14 ` [PATCH 04/19] mm: numa: define _PAGE_NUMA Mel Gorman
2012-11-06 18:35 ` Rik van Riel
2012-11-06 9:14 ` [PATCH 05/19] mm: numa: pte_numa() and pmd_numa() Mel Gorman
2012-11-13 9:54 ` Ingo Molnar
2012-11-13 11:24 ` Mel Gorman
2012-11-06 9:14 ` Mel Gorman [this message]
2012-11-13 10:07 ` [PATCH 06/19] mm: numa: teach gup_fast about pmd_numa Ingo Molnar
2012-11-13 11:37 ` Mel Gorman
2012-11-13 13:51 ` Ingo Molnar
2012-11-06 9:14 ` [PATCH 07/19] mm: numa: split_huge_page: transfer the NUMA type from the pmd to the pte Mel Gorman
2012-11-06 9:14 ` [PATCH 08/19] mm: numa: Create basic numa page hinting infrastructure Mel Gorman
2012-11-06 18:58 ` Rik van Riel
2012-11-07 10:38 ` Mel Gorman
2012-11-07 10:48 ` Rik van Riel
2012-11-07 11:00 ` Mel Gorman
2012-11-13 10:21 ` Ingo Molnar
2012-11-13 11:50 ` Mel Gorman
2012-11-13 13:49 ` Ingo Molnar
2012-11-13 14:26 ` Mel Gorman
2012-11-06 9:14 ` [PATCH 09/19] mm: mempolicy: Make MPOL_LOCAL a real policy Mel Gorman
2012-11-06 9:14 ` [PATCH 10/19] mm: mempolicy: Add MPOL_MF_NOOP Mel Gorman
2012-11-06 9:14 ` [PATCH 11/19] mm: mempolicy: Check for misplaced page Mel Gorman
2012-11-06 9:14 ` [PATCH 12/19] mm: migrate: Introduce migrate_misplaced_page() Mel Gorman
2012-11-06 19:10 ` Rik van Riel
2012-11-13 9:36 ` Ingo Molnar
2012-11-13 11:43 ` Ingo Molnar
2012-11-13 11:56 ` Mel Gorman
2012-11-13 14:49 ` Rik van Riel
2012-11-06 9:14 ` [PATCH 13/19] mm: mempolicy: Use _PAGE_NUMA to migrate pages Mel Gorman
2012-11-06 19:18 ` Rik van Riel
2012-11-07 12:32 ` Mel Gorman
2012-11-06 9:14 ` [PATCH 14/19] mm: mempolicy: Add MPOL_MF_LAZY Mel Gorman
2012-11-06 19:19 ` Rik van Riel
2012-11-13 10:25 ` Ingo Molnar
2012-11-13 12:02 ` Mel Gorman
2012-11-06 9:14 ` [PATCH 15/19] mm: numa: Add fault driven placement and migration Mel Gorman
2012-11-06 19:41 ` Rik van Riel
2012-11-07 10:49 ` Mel Gorman
2012-11-07 11:46 ` Rik van Riel
2012-11-13 10:45 ` Ingo Molnar
2012-11-13 12:09 ` Mel Gorman
2012-11-13 13:39 ` Ingo Molnar
2012-11-06 9:14 ` [PATCH 16/19] mm: numa: Add pte updates, hinting and migration stats Mel Gorman
2012-11-06 19:55 ` Rik van Riel
2012-11-07 10:57 ` Mel Gorman
2012-11-07 11:47 ` Rik van Riel
2012-11-06 9:14 ` [PATCH 17/19] mm: numa: Migrate on reference policy Mel Gorman
2012-11-07 11:56 ` Rik van Riel
2012-11-06 9:14 ` [PATCH 18/19] mm: sched: numa: Implement constant, per task Working Set Sampling (WSS) rate Mel Gorman
2012-11-06 19:55 ` Rik van Riel
2012-11-06 9:14 ` [PATCH 19/19] mm: sched: numa: Implement slow start for working set sampling Mel Gorman
2012-11-06 19:56 ` Rik van Riel
2012-11-07 9:27 ` [RFC PATCH 00/19] Foundation for automatic NUMA balancing Zhouping Liu
2012-11-07 15:25 ` Mel Gorman
2012-11-08 6:37 ` Zhouping Liu
2012-11-08 6:39 ` 杨竹
2012-11-08 7:03 ` Zhouping Liu
2012-11-09 14:42 ` Andrea Arcangeli
2012-11-09 16:12 ` Mel Gorman
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