Re: [RFC v1 1/2] mm/slab: add sheaves_enabled read-only sysfs file

[David Rientjes <rientjes@google.com>]

On Mon, 7 Apr 2025, Harry Yoo wrote:

> For user-space tools like slabinfo, it is difficult to determine whether
> a cache has sheaves enabled. Expose a read-only 'sheaves_enabled' sysfs
> file to indicate whether sheaves are enabled for a given cache.
> 

Thoughts on adding an entry to Documentation/ABI/testing/sysfs-kernel-slab 
for this one?

> Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
> ---
>  mm/slub.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index b5ea66cbbe68..32db440a8b05 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -8504,6 +8504,15 @@ static ssize_t remote_node_defrag_ratio_store(struct kmem_cache *s,
>  SLAB_ATTR(remote_node_defrag_ratio);
>  #endif
>  
> +static ssize_t sheaves_enabled_show(struct kmem_cache *s, char *buf)
> +{
> +	if (s->cpu_sheaves)
> +		return sysfs_emit(buf, "%u\n", 1);
> +	else
> +		return sysfs_emit(buf, "%u\n", 0);
> +}
> +SLAB_ATTR_RO(sheaves_enabled);
> +
>  #ifdef CONFIG_SLUB_STATS
>  static int show_stat(struct kmem_cache *s, char *buf, enum stat_item si)
>  {
> @@ -8656,6 +8665,7 @@ static struct attribute *slab_attrs[] = {
>  #ifdef CONFIG_NUMA
>  	&remote_node_defrag_ratio_attr.attr,
>  #endif
> +	&sheaves_enabled_attr.attr,
>  #ifdef CONFIG_SLUB_STATS
>  	&alloc_cpu_sheaf_attr.attr,
>  	&alloc_fastpath_attr.attr,
> -- 
> 2.43.0
> 
>