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Mikulas Patocka 05-28-2012 04:44 PM

dm optimize: reorder structure
 
dm-optimize: reorder structure

This reorder actually improves performance by 20% (from 39.1s to 32.8s)
on x86-64 quad core Opteron.

I have no explanation for this, possibly it makes some other entries are
better cache-aligned.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

---
drivers/md/dm.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

Index: linux-3.4-rc6-fast/drivers/md/dm.c
================================================== =================
--- linux-3.4-rc6-fast.orig/drivers/md/dm.c 2012-05-18 08:06:15.000000000 +0200
+++ linux-3.4-rc6-fast/drivers/md/dm.c 2012-05-18 08:21:52.000000000 +0200
@@ -139,6 +139,13 @@ struct mapped_device {
atomic_t holders;
atomic_t open_count;

+ /*
+ * The current mapping.
+ * Use dm_get_live_table{_fast} or take suspend_lock for
+ * dereference.
+ */
+ struct dm_table *map;
+
unsigned long flags;

struct request_queue *queue;
@@ -168,13 +175,6 @@ struct mapped_device {
struct workqueue_struct *wq;

/*
- * The current mapping.
- * Use dm_get_live_table{_fast} or take suspend_lock for
- * dereference.
- */
- struct dm_table *map;
-
- /*
* io objects are allocated from here.
*/
mempool_t *io_pool;

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