[PATCH v4 4/4] nvme: repack struct nvme_ns_head

[Daniel Wagner]

ns_id, lba_shift and ms are always accessed for every read/write I/O in
nvme_setup_rw. By grouping these variables into one cacheline we can
safe some cycles.

4k sequential reads:

           baseline   patched
Bandwidth: 1620       1634
IOPs       66345579   66910939

Signed-off-by: Daniel Wagner <dwagner@xxxxxxx>
---
 drivers/nvme/host/nvme.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 2b31641a97b9..4a4beaecc832 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -445,21 +445,21 @@ struct nvme_ns_head {
 	struct list_head	list;
 	struct srcu_struct      srcu;
 	struct nvme_subsystem	*subsys;
-	unsigned		ns_id;
 	struct nvme_ns_ids	ids;
 	struct list_head	entry;
 	struct kref		ref;
 	bool			shared;
 	int			instance;
 	struct nvme_effects_log *effects;
+	u64			nuse;
+	unsigned		ns_id;
 	int			lba_shift;
 	u16			ms;
 	u16			pi_size;
-	u16			sgs;
-	u32			sws;
-	u64			nuse;
 	u8			pi_type;
 	u8			guard_type;
+	u16			sgs;
+	u32			sws;
 #ifdef CONFIG_BLK_DEV_ZONED
 	u64			zsze;
 #endif
-- 
2.43.0