linux-kernel - Re: [PATCH 03/12] maple_tree: use percpu sheaves for maple_node

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Message-ID: <fbc20724-bec5-4a80-b77c-9bec445097cf@oracle.com>
Date: Tue, 2 Sep 2025 15:39:59 -0400
From: Sidhartha Kumar <sidhartha.kumar@...cle.com>
To: Vlastimil Babka <vbabka@...e.cz>,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        Matthew Wilcox <willy@...radead.org>,
        Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
        Jann Horn <jannh@...gle.com>, Pedro Falcato <pfalcato@...e.de>,
        Suren Baghdasaryan <surenb@...gle.com>
Cc: Harry Yoo <harry.yoo@...cle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        maple-tree@...ts.infradead.org, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 03/12] maple_tree: use percpu sheaves for maple_node_cache

On 9/1/25 7:08 AM, Vlastimil Babka wrote:
> Setup the maple_node_cache with percpu sheaves of size 32 to hopefully
> improve its performance. Note this will not immediately take advantage
> of sheaf batching of kfree_rcu() operations due to the maple tree using
> call_rcu with custom callbacks. The followup changes to maple tree will
> change that and also make use of the prefilled sheaves functionality.
> 
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
> Reviewed-by: Suren Baghdasaryan <surenb@...gle.com>

Reviewed-by: Sidhartha Kumar <sidhartha.kumar@...cle.com>

> ---
>   lib/maple_tree.c | 9 +++++++--
>   1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index b4ee2d29d7a962ca374467d0533185f2db3d35ff..a0db6bdc63793b8bbd544e246391d99e880dede3 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -6302,9 +6302,14 @@ bool mas_nomem(struct ma_state *mas, gfp_t gfp)
>   
>   void __init maple_tree_init(void)
>   {
> +	struct kmem_cache_args args = {
> +		.align  = sizeof(struct maple_node),
> +		.sheaf_capacity = 32,
> +	};
> +
>   	maple_node_cache = kmem_cache_create("maple_node",
> -			sizeof(struct maple_node), sizeof(struct maple_node),
> -			SLAB_PANIC, NULL);
> +			sizeof(struct maple_node), &args,
> +			SLAB_PANIC);
>   }
>   
>   /**
>