Hi,
在 2023/11/22 18:31, Yu Kuai 写道:
From: Ming Lei <ming.lei@xxxxxxxxxx>
The .bd_inode field of block_device is used in IO fast path of
blkdev_write_iter() and blkdev_llseek(), so it is more efficient to keep
it into the 1st cacheline.
.bd_openers is only touched in open()/close(), and .bd_size_lock is only
for updating bdev capacity, which is in slow path too.
So swap .bd_inode layout with .bd_openers & .bd_size_lock to move
.bd_inode into the 1st cache line.
Cc: Yu Kuai <yukuai3@xxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
include/linux/blk_types.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index d5c5e59ddbd2..f7d40692dd94 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -49,9 +49,10 @@ struct block_device {
bool bd_write_holder;
bool bd_has_submit_bio;
dev_t bd_dev;
+ struct inode *bd_inode; /* will die */
Now that we're here, and bdev->bd_inode is always point to the
field inode of struct bdev_inode, which is next to the field bdev,
and the comment "will die" have been exist for a long time.
Maybe I can try to replace all the reference of bdev->bd_inode with
a helper, and then remove this field, then it'll be acceptable to add
a new field "unsigned long bd_flags".
Thanks,
Kuai
+
atomic_t bd_openers;
spinlock_t bd_size_lock; /* for bd_inode->i_size updates */
- struct inode * bd_inode; /* will die */
void * bd_claiming;
void * bd_holder;
const struct blk_holder_ops *bd_holder_ops;
