[Cluster-devel] [GFS2 PATCH] GFS2: Don't add all glocks to the lru

[Steven Whitehouse]

Acked-by: Steven Whitehouse <swhiteho at redhat.com>

Steve.

On 16/06/15 19:31, Bob Peterson wrote:
> Hi,
>
> Regarding my previously posted patch:
> I decided it makes more sense not to single out rgrp glocks for
> exclusion from the lru list. It makes sense to also exclude the
> transaction glock, and "non-disk" glocks off the lru list as well.
> Therefore, I changed this to a generic "glops" flag so we could
> specify them on an individual basis.
>
> Patch description:
>
> The glocks used for resource groups often come and go hundreds of
> thousands of time per second. Adding them to the lru list just
> adds unnecessary contention for the lru_lock spin_lock, especially
> considering we're almost certainly going to re-use the glock and
> take it back off the lru microseconds later. We never want the
> glock shrinker to cull them anyway. This patch adds a new bit in
> the glops that determines which glock types get put onto the lru
> list and which ones don't.
>
> Regards,
>
> Bob Peterson
>
> Signed-off-by: Bob Peterson <rpeterso at redhat.com>
> ---
> diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
> index 0fa8062..a38e38f 100644
> --- a/fs/gfs2/glock.c
> +++ b/fs/gfs2/glock.c
> @@ -1076,7 +1076,8 @@ void gfs2_glock_dq(struct gfs2_holder *gh)
>   		    !test_bit(GLF_DEMOTE, &gl->gl_flags))
>   			fast_path = 1;
>   	}
> -	if (!test_bit(GLF_LFLUSH, &gl->gl_flags) && demote_ok(gl))
> +	if (!test_bit(GLF_LFLUSH, &gl->gl_flags) && demote_ok(gl) &&
> +	    (glops->go_flags & GLOF_LRU))
>   		gfs2_glock_add_to_lru(gl);
>   
>   	trace_gfs2_glock_queue(gh, 0);
> diff --git a/fs/gfs2/glops.c b/fs/gfs2/glops.c
> index fe91951..1249b2b 100644
> --- a/fs/gfs2/glops.c
> +++ b/fs/gfs2/glops.c
> @@ -561,7 +561,7 @@ const struct gfs2_glock_operations gfs2_inode_glops = {
>   	.go_lock = inode_go_lock,
>   	.go_dump = inode_go_dump,
>   	.go_type = LM_TYPE_INODE,
> -	.go_flags = GLOF_ASPACE,
> +	.go_flags = GLOF_ASPACE | GLOF_LRU,
>   };
>   
>   const struct gfs2_glock_operations gfs2_rgrp_glops = {
> @@ -584,10 +584,12 @@ const struct gfs2_glock_operations gfs2_freeze_glops = {
>   const struct gfs2_glock_operations gfs2_iopen_glops = {
>   	.go_type = LM_TYPE_IOPEN,
>   	.go_callback = iopen_go_callback,
> +	.go_flags = GLOF_LRU,
>   };
>   
>   const struct gfs2_glock_operations gfs2_flock_glops = {
>   	.go_type = LM_TYPE_FLOCK,
> +	.go_flags = GLOF_LRU,
>   };
>   
>   const struct gfs2_glock_operations gfs2_nondisk_glops = {
> @@ -596,7 +598,7 @@ const struct gfs2_glock_operations gfs2_nondisk_glops = {
>   
>   const struct gfs2_glock_operations gfs2_quota_glops = {
>   	.go_type = LM_TYPE_QUOTA,
> -	.go_flags = GLOF_LVB,
> +	.go_flags = GLOF_LVB | GLOF_LRU,
>   };
>   
>   const struct gfs2_glock_operations gfs2_journal_glops = {
> diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
> index 304a223..a1ec7c2 100644
> --- a/fs/gfs2/incore.h
> +++ b/fs/gfs2/incore.h
> @@ -225,6 +225,7 @@ struct gfs2_glock_operations {
>   	const unsigned long go_flags;
>   #define GLOF_ASPACE 1
>   #define GLOF_LVB    2
> +#define GLOF_LRU    4
>   };
>   
>   enum {
>