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

[Steven Whitehouse <swhiteho@redhat.com>]

Hi,

On 12/06/15 19:29, Bob Peterson wrote:
> Hi,
>
> The glocks used for resource groups often come and go hundreds of
> thousands of times 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 bypasses adding
> them to the lru.
>
> Regards,
>
> Bob Peterson
> Red Hat File Systems
>
> Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Acked-by: Steven Whitehouse <swhiteho@redhat.com>

Steve.
> ---
> diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
> index 0fa8062..1db06a5 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) &&
> +	    gl->gl_name.ln_type != LM_TYPE_RGRP)
>   		gfs2_glock_add_to_lru(gl);
>   
>   	trace_gfs2_glock_queue(gh, 0);
>