The patch titled
Subject: mm: adjust address_space_operations.migratepage() return code
has been added to the -mm tree. Its filename is
mm-adjust-address_space_operationsmigratepage-return-code.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: Rafael Aquini <aquini@xxxxxxxxxx>
Subject: mm: adjust address_space_operations.migratepage() return code
Memory fragmentation introduced by ballooning might reduce significantly
the number of 2MB contiguous memory blocks that can be used within a
guest, thus imposing performance penalties associated with the reduced
number of transparent huge pages that could be used by the guest workload.
This patchset follows the main idea discussed at 2012 LSFMMS session:
"Ballooning for transparent huge pages" -- http://lwn.net/Articles/490114/
to introduce the required changes to the virtio_balloon driver, as well as
the changes to the core compaction & migration bits, in order to make
those subsystems aware of ballooned pages and allow memory balloon pages
become movable within a guest, thus avoiding the aforementioned
fragmentation issue
Following are numbers that prove this patch benefits on allowing
compaction to be more effective at memory ballooned guests.
Results for STRESS-HIGHALLOC benchmark, from Mel Gorman's mmtests suite,
running on a 4gB RAM KVM guest which was ballooning 512mB RAM in 64mB
chunks, at every minute (inflating/deflating), while test was running:
===BEGIN stress-highalloc
STRESS-HIGHALLOC
highalloc-3.7 highalloc-3.7
rc4-clean rc4-patch
Pass 1 55.00 ( 0.00%) 62.00 ( 7.00%)
Pass 2 54.00 ( 0.00%) 62.00 ( 8.00%)
while Rested 75.00 ( 0.00%) 80.00 ( 5.00%)
MMTests Statistics: duration
3.7 3.7
rc4-clean rc4-patch
User 1207.59 1207.46
System 1300.55 1299.61
Elapsed 2273.72 2157.06
MMTests Statistics: vmstat
3.7 3.7
rc4-clean rc4-patch
Page Ins 3581516 2374368
Page Outs 11148692 10410332
Swap Ins 80 47
Swap Outs 3641 476
Direct pages scanned 37978 33826
Kswapd pages scanned 1828245 1342869
Kswapd pages reclaimed 1710236 1304099
Direct pages reclaimed 32207 31005
Kswapd efficiency 93% 97%
Kswapd velocity 804.077 622.546
Direct efficiency 84% 91%
Direct velocity 16.703 15.682
Percentage direct scans 2% 2%
Page writes by reclaim 79252 9704
Page writes file 75611 9228
Page writes anon 3641 476
Page reclaim immediate 16764 11014
Page rescued immediate 0 0
Slabs scanned 2171904 2152448
Direct inode steals 385 2261
Kswapd inode steals 659137 609670
Kswapd skipped wait 1 69
THP fault alloc 546 631
THP collapse alloc 361 339
THP splits 259 263
THP fault fallback 98 50
THP collapse fail 20 17
Compaction stalls 747 499
Compaction success 244 145
Compaction failures 503 354
Compaction pages moved 370888 474837
Compaction move failure 77378 65259
===END stress-highalloc
This patch:
Introduce MIGRATEPAGE_SUCCESS as the default return code for
address_space_operations.migratepage() method and documents the expected
return code for the same method in failure cases.
Signed-off-by: Rafael Aquini <aquini@xxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/hugetlbfs/inode.c | 4 ++--
include/linux/migrate.h | 7 +++++++
mm/migrate.c | 26 +++++++++++++-------------
3 files changed, 22 insertions(+), 15 deletions(-)
diff -puN fs/hugetlbfs/inode.c~mm-adjust-address_space_operationsmigratepage-return-code fs/hugetlbfs/inode.c
--- a/fs/hugetlbfs/inode.c~mm-adjust-address_space_operationsmigratepage-return-code
+++ a/fs/hugetlbfs/inode.c
@@ -582,11 +582,11 @@ static int hugetlbfs_migrate_page(struct
int rc;
rc = migrate_huge_page_move_mapping(mapping, newpage, page);
- if (rc)
+ if (rc != MIGRATEPAGE_SUCCESS)
return rc;
migrate_page_copy(newpage, page);
- return 0;
+ return MIGRATEPAGE_SUCCESS;
}
static int hugetlbfs_statfs(struct dentry *dentry, struct kstatfs *buf)
diff -puN include/linux/migrate.h~mm-adjust-address_space_operationsmigratepage-return-code include/linux/migrate.h
--- a/include/linux/migrate.h~mm-adjust-address_space_operationsmigratepage-return-code
+++ a/include/linux/migrate.h
@@ -7,6 +7,13 @@
typedef struct page *new_page_t(struct page *, unsigned long private, int **);
+/*
+ * Return values from addresss_space_operations.migratepage():
+ * - negative errno on page migration failure;
+ * - zero on page migration success;
+ */
+#define MIGRATEPAGE_SUCCESS 0
+
#ifdef CONFIG_MIGRATION
extern void putback_lru_pages(struct list_head *l);
diff -puN mm/migrate.c~mm-adjust-address_space_operationsmigratepage-return-code mm/migrate.c
--- a/mm/migrate.c~mm-adjust-address_space_operationsmigratepage-return-code
+++ a/mm/migrate.c
@@ -286,7 +286,7 @@ static int migrate_page_move_mapping(str
expected_count += 1;
if (page_count(page) != expected_count)
return -EAGAIN;
- return 0;
+ return MIGRATEPAGE_SUCCESS;
}
spin_lock_irq(&mapping->tree_lock);
@@ -356,7 +356,7 @@ static int migrate_page_move_mapping(str
}
spin_unlock_irq(&mapping->tree_lock);
- return 0;
+ return MIGRATEPAGE_SUCCESS;
}
/*
@@ -372,7 +372,7 @@ int migrate_huge_page_move_mapping(struc
if (!mapping) {
if (page_count(page) != 1)
return -EAGAIN;
- return 0;
+ return MIGRATEPAGE_SUCCESS;
}
spin_lock_irq(&mapping->tree_lock);
@@ -399,7 +399,7 @@ int migrate_huge_page_move_mapping(struc
page_unfreeze_refs(page, expected_count - 1);
spin_unlock_irq(&mapping->tree_lock);
- return 0;
+ return MIGRATEPAGE_SUCCESS;
}
/*
@@ -486,11 +486,11 @@ int migrate_page(struct address_space *m
rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode);
- if (rc)
+ if (rc != MIGRATEPAGE_SUCCESS)
return rc;
migrate_page_copy(newpage, page);
- return 0;
+ return MIGRATEPAGE_SUCCESS;
}
EXPORT_SYMBOL(migrate_page);
@@ -513,7 +513,7 @@ int buffer_migrate_page(struct address_s
rc = migrate_page_move_mapping(mapping, newpage, page, head, mode);
- if (rc)
+ if (rc != MIGRATEPAGE_SUCCESS)
return rc;
/*
@@ -549,7 +549,7 @@ int buffer_migrate_page(struct address_s
} while (bh != head);
- return 0;
+ return MIGRATEPAGE_SUCCESS;
}
EXPORT_SYMBOL(buffer_migrate_page);
#endif
@@ -665,7 +665,7 @@ static int move_to_new_page(struct page
else
rc = fallback_migrate_page(mapping, newpage, page, mode);
- if (rc) {
+ if (rc != MIGRATEPAGE_SUCCESS) {
newpage->mapping = NULL;
} else {
if (remap_swapcache)
@@ -814,7 +814,7 @@ skip_unmap:
put_anon_vma(anon_vma);
uncharge:
- mem_cgroup_end_migration(mem, page, newpage, rc == 0);
+ mem_cgroup_end_migration(mem, page, newpage, rc == MIGRATEPAGE_SUCCESS);
unlock:
unlock_page(page);
out:
@@ -987,7 +987,7 @@ int migrate_pages(struct list_head *from
case -EAGAIN:
retry++;
break;
- case 0:
+ case MIGRATEPAGE_SUCCESS:
break;
default:
/* Permanent failure */
@@ -1001,7 +1001,7 @@ out:
if (!swapwrite)
current->flags &= ~PF_SWAPWRITE;
- if (rc)
+ if (rc != MIGRATEPAGE_SUCCESS)
return rc;
return nr_failed + retry;
@@ -1024,7 +1024,7 @@ int migrate_huge_page(struct page *hpage
/* try again */
cond_resched();
break;
- case 0:
+ case MIGRATEPAGE_SUCCESS:
goto out;
default:
rc = -EIO;
_
Patches currently in -mm which might be from aquini@xxxxxxxxxx are
mm-adjust-address_space_operationsmigratepage-return-code.patch
mm-redefine-address_spaceassoc_mapping.patch
mm-introduce-a-common-interface-for-balloon-pages-mobility.patch
mm-introduce-compaction-and-migration-for-ballooned-pages.patch
virtio_balloon-introduce-migration-primitives-to-balloon-pages.patch
mm-introduce-putback_movable_pages.patch
mm-add-vm-event-counters-for-balloon-pages-compaction.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
