Re: [linus:master] [xfs] 9b64ca202f: fxmark.ssd_xfs_DRBH_4_bufferedio.works/sec 24.1% regression

[Christoph Hellwig]

On Thu, Jul 16, 2026 at 09:13:19PM +0800, kernel test robot wrote:
> 
> 
> Hello,
> 
> kernel test robot noticed a 24.1% regression of fxmark.ssd_xfs_DRBH_4_bufferedio.works/sec on:
> 

This looks really odd.  While the patch adds a bit more computation,
that is very cheap shifting and masking.  So the only theory I have here
is that this somehow affects the inode data layout.  Can you re-run this
with the patch below applied on top of commit
9b64ca202f364a6bf8e19bdd20953bc2d776c67f ?

diff --git a/fs/xfs/libxfs/xfs_inode_buf.h b/fs/xfs/libxfs/xfs_inode_buf.h
index 57192adc7744..319e83d4a087 100644
--- a/fs/xfs/libxfs/xfs_inode_buf.h
+++ b/fs/xfs/libxfs/xfs_inode_buf.h
@@ -15,6 +15,7 @@ struct xfs_dinode;
  */
 struct xfs_imap {
 	xfs_agblock_t	im_agbno;	/* starting agbno of inode cluster */
+	uint32_t	__im_pad;
 	unsigned short	im_boffset;	/* offset in inode cluster in bytes */
 };