[Cluster-devel] [GFS2 PATCH] Optimize glock multiple-dequeue code

[Steven Whitehouse <swhiteho@redhat.com>]

Hi,

On Thu, 2011-03-10 at 11:41 -0500, Bob Peterson wrote:
> Hi,
> 
> This is a small patch that optimizes multiple glock dequeue
> operations.  It changes the unlock order to be more efficient
> and makes it easier for lock debugging tools to unravel.  It
> also eliminates the need for the temp variable x, although
> that would likely be optimized out.
> 
> Regards,
> 
> Bob Peterson
> Red Hat File Systems
> 
> Signed-off-by: Bob Peterson <rpeterso@redhat.com> 
> --
>  fs/gfs2/glock.c |   12 ++++--------
>  1 files changed, 4 insertions(+), 8 deletions(-)
> 
I'm still not convinced that this really makes a difference, but it
doesn't do any harm either, so I've pushed it into the -nmw tree,

Steve.

> diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
> index 3f45a14..8648409 100644
> --- a/fs/gfs2/glock.c
> +++ b/fs/gfs2/glock.c
> @@ -1248,10 +1248,8 @@ int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
>  
>  void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
>  {
> -	unsigned int x;
> -
> -	for (x = 0; x < num_gh; x++)
> -		gfs2_glock_dq(&ghs[x]);
> +	while (num_gh--)
> +		gfs2_glock_dq(&ghs[num_gh]);
>  }
>  
>  /**
> @@ -1263,10 +1261,8 @@ void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
>  
>  void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
>  {
> -	unsigned int x;
> -
> -	for (x = 0; x < num_gh; x++)
> -		gfs2_glock_dq_uninit(&ghs[x]);
> +	while (num_gh--)
> +		gfs2_glock_dq_uninit(&ghs[num_gh]);
>  }
>  
>  void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
>