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 06/31] mm: numa: teach gup_fast about pmd_numa
Date: Tue, 13 Nov 2012 11:12:35 +0000 [thread overview]
Message-ID: <1352805180-1607-7-git-send-email-mgorman@suse.de> (raw)
In-Reply-To: <1352805180-1607-1-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
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2012-11-13 11:13 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-13 11:12 [RFC PATCH 00/31] Foundation for automatic NUMA balancing V2 Mel Gorman
2012-11-13 11:12 ` [PATCH 01/31] mm: compaction: Move migration fail/success stats to migrate.c Mel Gorman
2012-11-13 11:12 ` [PATCH 02/31] mm: migrate: Add a tracepoint for migrate_pages Mel Gorman
2012-11-13 11:12 ` [PATCH 03/31] mm: compaction: Add scanned and isolated counters for compaction Mel Gorman
2012-11-13 11:12 ` [PATCH 04/31] mm: numa: define _PAGE_NUMA Mel Gorman
2012-11-13 11:12 ` [PATCH 05/31] mm: numa: pte_numa() and pmd_numa() Mel Gorman
2012-11-13 11:12 ` Mel Gorman [this message]
2012-11-13 11:12 ` [PATCH 07/31] mm: numa: split_huge_page: transfer the NUMA type from the pmd to the pte Mel Gorman
2012-11-14 17:13 ` Rik van Riel
2012-11-13 11:12 ` [PATCH 08/31] mm: numa: Create basic numa page hinting infrastructure Mel Gorman
2012-11-13 11:12 ` [PATCH 09/31] mm: mempolicy: Make MPOL_LOCAL a real policy Mel Gorman
2012-11-13 11:12 ` [PATCH 10/31] mm: mempolicy: Add MPOL_MF_NOOP Mel Gorman
2012-11-13 11:12 ` [PATCH 11/31] mm: mempolicy: Check for misplaced page Mel Gorman
2012-11-13 11:12 ` [PATCH 12/31] mm: migrate: Introduce migrate_misplaced_page() Mel Gorman
2012-11-13 11:12 ` [PATCH 13/31] mm: mempolicy: Use _PAGE_NUMA to migrate pages Mel Gorman
2012-11-13 11:12 ` [PATCH 14/31] mm: mempolicy: Add MPOL_MF_LAZY Mel Gorman
2012-11-13 11:12 ` [PATCH 15/31] mm: numa: Add fault driven placement and migration Mel Gorman
2012-11-13 11:12 ` [PATCH 16/31] mm: numa: Only call task_numa_placement for misplaced pages Mel Gorman
2012-11-14 17:58 ` Rik van Riel
2012-11-14 18:18 ` Mel Gorman
2012-11-13 11:12 ` [PATCH 17/31] mm: numa: Avoid double faulting after migrating misplaced page Mel Gorman
2012-11-14 18:00 ` Rik van Riel
2012-11-13 11:12 ` [PATCH 18/31] mm: sched: numa: Implement constant, per task Working Set Sampling (WSS) rate Mel Gorman
2012-11-13 11:12 ` [PATCH 19/31] mm: sched: numa: Implement slow start for working set sampling Mel Gorman
2012-11-13 11:12 ` [PATCH 20/31] mm: numa: Add pte updates, hinting and migration stats Mel Gorman
2012-11-13 11:12 ` [PATCH 21/31] mm: numa: Migrate on reference policy Mel Gorman
2012-11-13 11:12 ` [PATCH 22/31] x86: mm: only do a local tlb flush in ptep_set_access_flags() Mel Gorman
2012-11-13 11:12 ` [PATCH 23/31] x86: mm: drop TLB flush from ptep_set_access_flags Mel Gorman
2012-11-13 11:12 ` [PATCH 24/31] mm,generic: only flush the local TLB in ptep_set_access_flags Mel Gorman
2012-11-13 11:12 ` [PATCH 25/31] sched: numa: Introduce tsk_home_node() Mel Gorman
2012-11-13 11:12 ` [PATCH 26/31] sched: numa: Make mempolicy home-node aware Mel Gorman
2012-11-14 18:22 ` Rik van Riel
2012-11-14 18:50 ` Mel Gorman
2012-11-13 11:12 ` [PATCH 27/31] sched: numa: Make find_busiest_queue() a method Mel Gorman
2012-11-14 18:25 ` Rik van Riel
2012-11-13 11:12 ` [PATCH 28/31] sched: numa: Implement home-node awareness Mel Gorman
2012-11-13 11:12 ` [PATCH 29/31] sched: numa: CPU follows memory Mel Gorman
2012-11-14 11:20 ` Mel Gorman
2012-11-13 11:12 ` [PATCH 30/31] mm: numa: Introduce last_nid to the page frame Mel Gorman
2012-11-13 11:13 ` [PATCH 31/31] mm: numa: Use a two-stage filter to restrict pages being migrated for unlikely task<->node relationships Mel Gorman
2012-11-13 15:14 ` [RFC PATCH 00/31] Foundation for automatic NUMA balancing V2 Ingo Molnar
2012-11-13 15:42 ` Mel Gorman
2012-11-13 17:27 ` Ingo Molnar
2012-11-14 4:09 ` Rik van Riel
2012-11-14 12:24 ` Mel Gorman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1352805180-1607-7-git-send-email-mgorman@suse.de \
--to=mgorman@suse.de \
--cc=a.p.zijlstra@chello.nl \
--cc=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=hannes@cmpxchg.org \
--cc=hughd@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mingo@kernel.org \
--cc=riel@redhat.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).