linux-kernel - Re: [PATCH 04/12] mm, slub: retain no free slabs on partial list with CONFIG_SLUB

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Date:   Thu, 24 Nov 2022 20:38:55 +0900
From:   Hyeonggon Yoo <42.hyeyoo@...il.com>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Pekka Enberg <penberg@...nel.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Matthew Wilcox <willy@...radead.org>, patches@...ts.linux.dev,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 04/12] mm, slub: retain no free slabs on partial list
 with CONFIG_SLUB_TINY

On Mon, Nov 21, 2022 at 06:11:54PM +0100, Vlastimil Babka wrote:
> SLUB will leave a number of slabs on the partial list even if they are
> empty, to avoid some slab freeing and reallocation. The goal of
> CONFIG_SLUB_TINY is to minimize memory overhead, so set the limits to 0
> for immediate slab page freeing.
> 
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
> ---
>  mm/slub.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index ab085aa2f1f0..917b79278bad 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -241,6 +241,7 @@ static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s)
>  /* Enable to log cmpxchg failures */
>  #undef SLUB_DEBUG_CMPXCHG
>  
> +#ifndef CONFIG_SLUB_TINY
>  /*
>   * Minimum number of partial slabs. These will be left on the partial
>   * lists even if they are empty. kmem_cache_shrink may reclaim them.
> @@ -253,6 +254,10 @@ static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s)
>   * sort the partial list by the number of objects in use.
>   */
>  #define MAX_PARTIAL 10
> +#else
> +#define MIN_PARTIAL 0
> +#define MAX_PARTIAL 0
> +#endif
>  
>  #define DEBUG_DEFAULT_FLAGS (SLAB_CONSISTENCY_CHECKS | SLAB_RED_ZONE | \
>  				SLAB_POISON | SLAB_STORE_USER)
> -- 
> 2.38.1
> 

Reviewed-by: Hyeonggon Yoo <42.hyeyoo@...il.com>

-- 
Thanks,
Hyeonggon