Subject: + mm-compaction-avoid-isolating-pinned-pages.patch added to -mm tree
To: rientjes@xxxxxxxxxx,gthelen@xxxxxxxxxx,hughd@xxxxxxxxxx,iamjoonsoo.kim@xxxxxxx,mgorman@xxxxxxx,riel@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Thu, 06 Feb 2014 13:37:45 -0800
The patch titled
Subject: mm, compaction: avoid isolating pinned pages
has been added to the -mm tree. Its filename is
mm-compaction-avoid-isolating-pinned-pages.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-avoid-isolating-pinned-pages.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-avoid-isolating-pinned-pages.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: David Rientjes <rientjes@xxxxxxxxxx>
Subject: mm, compaction: avoid isolating pinned pages
Page migration will fail for memory that is pinned in memory with, for
example, get_user_pages(). In this case, it is unnecessary to take
zone->lru_lock or isolating the page and passing it to page migration
which will ultimately fail.
This is a racy check, the page can still change from under us, but in
that case we'll just fail later when attempting to move the page.
This avoids very expensive memory compaction when faulting transparent
hugepages after pinning a lot of memory with a Mellanox driver.
On a 128GB machine and pinning ~120GB of memory, before this patch we
see the enormous disparity in the number of page migration failures
because of the pinning (from /proc/vmstat):
compact_pages_moved 8450
compact_pagemigrate_failed 15614415
0.05% of pages isolated are successfully migrated and explicitly
triggering memory compaction takes 102 seconds. After the patch:
compact_pages_moved 9197
compact_pagemigrate_failed 7
99.9% of pages isolated are now successfully migrated in this
configuration and memory compaction takes less than one second.
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Acked-by: Hugh Dickins <hughd@xxxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Greg Thelen <gthelen@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/compaction.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff -puN mm/compaction.c~mm-compaction-avoid-isolating-pinned-pages mm/compaction.c
--- a/mm/compaction.c~mm-compaction-avoid-isolating-pinned-pages
+++ a/mm/compaction.c
@@ -578,6 +578,15 @@ isolate_migratepages_range(struct zone *
continue;
}
+ /*
+ * Migration will fail if an anonymous page is pinned in memory,
+ * so avoid taking lru_lock and isolating it unnecessarily in an
+ * admittedly racy check.
+ */
+ if (!page_mapping(page) &&
+ page_count(page) > page_mapcount(page))
+ continue;
+
/* Check if it is ok to still hold the lock */
locked = compact_checklock_irqsave(&zone->lru_lock, &flags,
locked, cc);
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
documentation-kernel-parameterstxt-fix-memmap=-language.patch
mm-__set_page_dirty_nobuffers-uses-spin_lock_irqseve-instead-of-spin_lock_irq.patch
numa-mem-hotplug-initialize-numa_kernel_nodes-in-numa_clear_kernel_node_hotplug.patch
numa-mem-hotplug-fix-array-index-overflow-when-synchronizing-nid-to-memblockreserved.patch
mm-__set_page_dirty-uses-spin_lock_irqsave-instead-of-spin_lock_irq.patch
mm-slub-list_lock-may-not-be-held-in-some-circumstances.patch
fs-filec-fdtable-avoid-triggering-ooms-from-alloc_fdmem.patch
mm-page_alloc-make-first_page-visible-before-pagetail.patch
kthread-ensure-locality-of-task_struct-allocations.patch
mm-slab-slub-use-page-list-consistently-instead-of-page-lru.patch
mm-compaction-ignore-pageblock-skip-when-manually-invoking-compaction.patch
mm-vmscan-shrink_slab-rename-max_pass-freeable.patch
mm-hugetlb-mark-some-bootstrap-functions-as-__init.patch
mm-compaction-avoid-isolating-pinned-pages.patch
mm-utilc-add-kstrimdup.patch
cpusets-allocate-heap-only-when-required.patch
linux-next.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
