Hi,
在 2023/11/21 19:21, Ming Lei 写道:
On Tue, Nov 21, 2023 at 07:12:44PM +0800, Yu Kuai wrote:
Hi,
在 2023/11/21 18:11, Ming Lei 写道:
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.
This patch looks good, do you want me do take it for a v3 for the
other patchset?
Yeah, please take it.
Ok
And by the way, can we also move 'int bd_writers' to near 'atomic_t
bd_fsfreeze_count' to save 8 bytes(int 64bit platform)?
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 07abd0165226..a47ab9249bdd 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -63,11 +63,11 @@ struct block_device {
int bd_holders;
struct kobject *bd_holder_dir;
+ int bd_writers;
atomic_t bd_fsfreeze_count; /* number of freeze
requests */
struct mutex bd_fsfreeze_mutex; /* serialize freeze/thaw
*/
struct partition_meta_info *bd_meta_info;
- int bd_writers;
Which tree are you talking about? I don't see 'bd_writers' in both
linus tree and block-6.7, and for-6.8/block isn't open yet.
This is introduced from commit dc85fbc92365 ("block: Add config option
to not allow writing to mounted devices") from linux-next by Jan.
Thanks,
Kuai
Thanks,
Ming
.
