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b=pIf2SEbz/mNFJt6nVnG6K3cTn1Sgk++2rlTnZfyRU4RFEZoUNcfa1Z9qLoD8up1d0 xn5f3GZUCBv15DrJNsUCU2qJ3Q+kMpsOSM+pv5r0v3IWlraaWTjNKkFb6R1NYwCC+j pH/8t2kt6owcvjD8/ObU5a2+UMOkY4rVcvJRt+XZf3pJ6qVe9xKW1uRbcP3Pz4tNiW 8KecPG3X53ainVtCQUwvF4e1BVWgtSfPb6uRonqDshhsg4jX6prkM37IxP8Wd0WrfJ 5B/tajIcdGQyWsXv8qBqKV79NCLFx86hnS8WiX4SrUgDsfW16ZefwcvjVkpYh3q9sp ahHxHqn8jSu9A== Message-ID: <39cecc4a-608f-4129-a68f-fc23987c8591@kernel.org> Date: Mon, 16 Mar 2026 14:19:16 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: "Vlastimil Babka (SUSE)" Subject: Re: [PATCH 1/3] slab: decouple pointer to barn from kmem_cache_node Content-Language: en-US To: Harry Yoo Cc: Ming Lei , Hao Li , Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260311-b4-slab-memoryless-barns-v1-0-70ab850be4ce@kernel.org> <20260311-b4-slab-memoryless-barns-v1-1-70ab850be4ce@kernel.org> <94d89d84-c009-470e-a401-1ac75228cd92@kernel.org> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 77AF9C0003 X-Stat-Signature: 36nbrw6enwdiofyd3x5t8pjokom7opba X-Rspam-User: X-HE-Tag: 1773667161-675042 X-HE-Meta: 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 Dc/4EsOd tY27Q Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/13/26 12:48, Harry Yoo wrote: > On Fri, Mar 13, 2026 at 10:46:15AM +0100, Vlastimil Babka (SUSE) wrote: >> On 3/13/26 10:27, Harry Yoo wrote: >> > On Wed, Mar 11, 2026 at 09:25:55AM +0100, Vlastimil Babka (SUSE) wrote: >> >> diff --git a/mm/slub.c b/mm/slub.c >> >> index 20cb4f3b636d..609a183f8533 100644 >> >> --- a/mm/slub.c >> >> +++ b/mm/slub.c >> >> @@ -436,26 +436,24 @@ struct kmem_cache_node { >> >> /* >> >> - * Get the barn of the current cpu's closest memory node. It may not exist on >> >> - * systems with memoryless nodes but without CONFIG_HAVE_MEMORYLESS_NODES >> >> + * Get the barn of the current cpu's memory node. It may be a memoryless node. >> >> */ >> >> static inline struct node_barn *get_barn(struct kmem_cache *s) >> >> { >> >> - struct kmem_cache_node *n = get_node(s, numa_mem_id()); >> >> - >> >> - if (!n) >> >> - return NULL; >> >> - >> >> - return n->barn; >> >> + return get_barn_node(s, numa_node_id()); >> >> } >> > >> > Previously, memoryless nodes on architectures w/ CONFIG_HAVE_MEMORYLESS_NODES >> > shared the barn of the nearest NUMA node with memory. >> > >> > But now memoryless nodes will have their own barns (after patch 2) >> > regardless of CONFIG_HAVE_MEMORYLESS_NODES, and that's intentional, right? >> >> Yeah it improves their caching capacity, but good point, will mention it in >> the changelog. > > Thanks! just wanted to check that it was intentional. I wanted to update the changelog as promised. But realized that the change from numa_node_id() to numa_node_id() in get_barn() should actually be done only in patch 2, so I will move it there. In patch 1 that would mean no barns with CONFIG_HAVE_MEMORYLESS_NODES and thus a performance bisection hazard. > with that, please feel free to add: > Reviewed-by: Harry Yoo Thanks!