[PATCH v6 6/6] nvme: repack struct nvme_ns_head

Daniel Wagner
2023-12-18T17:00:12Z

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

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
---
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 6211f18c53c7..3dbd187896d8 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -440,21 +440,21 @@ 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