[Cluster-devel] [GFS2 Patch] GFS2: Sort the ordered write list

[Steven Whitehouse <swhiteho@redhat.com>]

Hi,

Now in the -nmw git tree. Thanks,

Steve.

On Tue, 2012-02-14 at 14:49 -0500, Bob Peterson wrote:
> Hi,
> 
> This patch sorts the ordered write list for GFS2 writes.
> This increases the throughput for simultaneous writes.
> For example, if you have ten processes, all doing:
> dd if=/dev/zero of=/mnt/gfs2/fileX
> on different files, the throughput will be much better.
> 
> Regards,
> 
> Bob Peterson
> Red Hat File Systems
> 
> Signed-off-by: Bob Peterson <rpeterso@redhat.com> 
> --
> GFS2: Sort the ordered write list
> 
> This patch sorts the ordered write list by block number to speed up
> writes.
> 
> diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
> index 4d31379..b8fe7b7 100644
> --- a/fs/gfs2/log.c
> +++ b/fs/gfs2/log.c
> @@ -19,6 +19,7 @@
>  #include <linux/freezer.h>
>  #include <linux/bio.h>
>  #include <linux/writeback.h>
> +#include <linux/list_sort.h>
>  
>  #include "gfs2.h"
>  #include "incore.h"
> @@ -566,6 +567,20 @@ static void log_flush_commit(struct gfs2_sbd *sdp)
>  	log_write_header(sdp, 0, 0);
>  }
>  
> +int bd_cmp(void *priv, struct list_head *a, struct list_head *b)
> +{
> +	struct gfs2_bufdata *bda, *bdb;
> +
> +	bda = list_entry(a, struct gfs2_bufdata, bd_le.le_list);
> +	bdb = list_entry(b, struct gfs2_bufdata, bd_le.le_list);
> +
> +	if (bda->bd_bh->b_blocknr < bdb->bd_bh->b_blocknr)
> +		return -1;
> +	if (bda->bd_bh->b_blocknr > bdb->bd_bh->b_blocknr)
> +		return 1;
> +	return 0;
> +}
> +
>  static void gfs2_ordered_write(struct gfs2_sbd *sdp)
>  {
>  	struct gfs2_bufdata *bd;
> @@ -573,6 +588,7 @@ static void gfs2_ordered_write(struct gfs2_sbd *sdp)
>  	LIST_HEAD(written);
>  
>  	gfs2_log_lock(sdp);
> +	list_sort(NULL, &sdp->sd_log_le_ordered, &bd_cmp);
>  	while (!list_empty(&sdp->sd_log_le_ordered)) {
>  		bd = list_entry(sdp->sd_log_le_ordered.next, struct gfs2_bufdata, bd_le.le_list);
>  		list_move(&bd->bd_le.le_list, &written);