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Wed, 2 Apr 2025 09:51:19 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id +DltCZcI7WdJTAAAD6G6ig (envelope-from ); Wed, 02 Apr 2025 09:51:19 +0000 Date: Wed, 2 Apr 2025 11:51:17 +0200 From: Oscar Salvador To: Rakie Kim Cc: gourry@gourry.net, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, joshua.hahnjy@gmail.com, dan.j.williams@intel.com, ying.huang@linux.alibaba.com, david@redhat.com, Jonathan.Cameron@huawei.com, kernel_team@skhynix.com, honggyu.kim@sk.com, yunjeong.mun@sk.com Subject: Re: [PATCH v5 3/3] mm/mempolicy: Support memory hotplug in weighted interleave Message-ID: References: <20250402014906.1086-1-rakie.kim@sk.com> <20250402014906.1086-4-rakie.kim@sk.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250402014906.1086-4-rakie.kim@sk.com> X-Rspamd-Queue-Id: 7E362180007 X-Rspamd-Server: rspam05 X-Rspam-User: X-Stat-Signature: ofhkno33hc3xa744e96iwkb78w9xykby X-HE-Tag: 1743587481-936792 X-HE-Meta: U2FsdGVkX18Mo2ICNtOfJcAXyvWj597EECfs5eM6kCBqib/joYwPsRGwkWavtB0m+7TlE5mRC8tTYZw52qi2FRGS9AIVBnsBO5/p8jS69glgW8HRTpBqtm05ez4YBzqa0mC16KIN16P1tVaa1rlKYZXLRngIHKLZgVG+7RMtMGJwi85WOwWY3BKHlWNpi2ZteAeLjgJYxtws8Kca1dm6kzIqshCRPGU510u+utHO9U8aYLLy24njyXwwnRBqmS1lLKjapUt+ly8CYgIQ2SJRfdYfjyof5vRUMaiiE3/eYvT9ESyM3wvi4aZrkibxNbaihsjah9QjkSi6eH8uTjPiVWizto9iihgN/4NQ+UINUikwQQF1eV1q5Nozb82K06SOxITCdF1JmkBsQJcTrrsbukTJA9rPujQrORTHWK+En3qaQQe3RIytg/zjyw2kIpokkC3RvpvBeOYmbBSDHNr3raIeoJLkTwwWwwCcK6hU0x1Ay4AaS68k9OoRRB0hFSjeE6CcRkWfsk0xcRjtUzFQhd+wFFx/Z7oqL/gUBAfHNpfWkKb9SfbFX9vzje8KApcKmyqbz1ZL/6413V2xeIkx03kynqIJ+gVYhQxsFf3i6J222h7xWDsowqBqsV3eeMUHY0fT3kL9tzcSTS+HB9ZZh4nXXqqH3ipYZ6deEgBOMhdN5vOTSzQiZII8TI6f8LU/wjWvylcOdaIpoMObxrInVTgqYvqTA/7gBoz0PRSOQVCU6RZR7r4DqLG0KGV3AmXb3h2LjiFjiVtG9j0OFc5YhmHA2dgIOu0o68YxIgxvfMYFv8sOHAkcjTVzlK5t29P3pMrreyrvZO8Jjg7BakU8mn9bFhS720AsW0PEBZI6+3/OzZSCRdhKysGn3f0btxdA2W/lMhT3nrwKyPfWqtMwCaGRhToA863HbbTy8+UjWw08jb2QuqBWKwaQMTU0SCwpqBxUK8pILtLq7MhP63e PbU1psxX nUu2e+GvBvsnpxWM= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Apr 02, 2025 at 10:49:04AM +0900, Rakie Kim wrote: > The weighted interleave policy distributes page allocations across multiple > NUMA nodes based on their performance weight, thereby improving memory > bandwidth utilization. The weight values for each node are configured > through sysfs. > > Previously, sysfs entries for configuring weighted interleave were created > for all possible nodes (N_POSSIBLE) at initialization, including nodes that > might not have memory. However, not all nodes in N_POSSIBLE are usable at > runtime, as some may remain memoryless or offline. > This led to sysfs entries being created for unusable nodes, causing > potential misconfiguration issues. > > To address this issue, this patch modifies the sysfs creation logic to: > 1) Limit sysfs entries to nodes that are online and have memory, avoiding > the creation of sysfs entries for nodes that cannot be used. > 2) Support memory hotplug by dynamically adding and removing sysfs entries > based on whether a node transitions into or out of the N_MEMORY state. > > Additionally, the patch ensures that sysfs attributes are properly managed > when nodes go offline, preventing stale or redundant entries from persisting > in the system. > > By making these changes, the weighted interleave policy now manages its > sysfs entries more efficiently, ensuring that only relevant nodes are > considered for interleaving, and dynamically adapting to memory hotplug > events. > > Signed-off-by: Rakie Kim > Signed-off-by: Honggyu Kim > Signed-off-by: Yunjeong Mun Sorry to jump at v5, and maybe this was already discussed but: > +static int wi_node_notifier(struct notifier_block *nb, > + unsigned long action, void *data) > +{ > + int err; > + struct memory_notify *arg = data; > + int nid = arg->status_change_nid; > + > + if (nid < 0) > + goto notifier_end; > + > + switch(action) { > + case MEM_ONLINE: > + err = sysfs_wi_node_add(nid); > + if (err) { > + pr_err("failed to add sysfs [node%d]\n", nid); > + return NOTIFY_BAD; > + } > + break; > + case MEM_OFFLINE: > + if (!node_state(nid, N_MEMORY)) > + sysfs_wi_node_release(nid); This check is not needed. If status_change_nid is different than NUMA_NO_NODE, it means that the memory state of the numa node was effectively changed. So doing: case MEM_OFFLINE: sysfs_wi_node_release(nid) is enough. -- Oscar Salvador SUSE Labs