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Tue, 19 Aug 2025 06:15:09 +0000 Message-ID: Date: Tue, 19 Aug 2025 08:15:09 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCHv2 2/4] nvme: extend show-topology command to add support for multipath To: Nilay Shroff , linux-nvme@lists.infradead.org Cc: dwagner@suse.de, kbusch@kernel.org, gjoyce@ibm.com References: <20250812125614.164445-1-nilay@linux.ibm.com> <20250812125614.164445-3-nilay@linux.ibm.com> <93be5b21-8897-44d3-a590-42ba8f1b6abb@suse.de> Content-Language: en-US From: Hannes Reinecke In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Spamd-Result: default: False [-4.51 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; TO_DN_SOME(0.00)[]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; RCVD_TLS_ALL(0.00)[]; RCPT_COUNT_FIVE(0.00)[5]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,suse.de:mid,suse.de:dkim,suse.de:email]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:104:10:150:64:97:from,2a07:de40:b281:106:10:150:64:167:received]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Queue-Id: 11CB52124F X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250818_231511_635331_59D02DFC X-CRM114-Status: GOOD ( 14.42 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 8/19/25 06:49, Nilay Shroff wrote: > > > On 8/18/25 12:52 PM, Hannes Reinecke wrote: >> On 8/12/25 14:56, Nilay Shroff wrote: >>> This commit enhances the show-topology command by adding support for >>> NVMe multipath. With this change, users can now list all paths to a >>> namespace from its corresponding head node device. Each NVMe path >>> entry then also includes additional details such as ANA state, NUMA >>> node, and queue depth, improving visibility into multipath configs. >>> This information can be particularly helpful for debugging and >>> analyzing NVMe multipath setups. >>> >>> To support this functionality, the "--ranking" option of the nvme >>> show-topology command has been extended with a new sub-option: >>> "multipath". >>> >>> Since this enhancement is specific to NVMe multipath, the iopolicy >>> configured under each subsystem is now always displayed. Previously, >>> iopolicy was shown only with nvme show-topology verbose output, but >>> it is now included by default to improve usability and provide better >>> context when reviewing multipath configurations via show-topology. >>> >>> With this update, users can view the multipath topology of a multi >>> controller/port NVMe disk using: >>> >>> $ nvme show-topology -r multipath >>> >>> nvme-subsys2 - NQN=nvmet_subsystem >>>                 hostnqn=nqn.2014-08.org.nvmexpress:uuid:12b49f6e-0276-4746-b10c-56815b7e6dc2 >>>                 iopolicy=numa >>> >>>            _ _ _ >>>           /              _ _ _ >>>          /              /      _ _ _ >>>         /              /      /  _ _ _ >>>        |              /      /  / >>>   +- nvme2n1 (ns 1)  /      /  / >>>   \                 |      |  | >>>    +- nvme2c2n1 optimized 1,2 0 nvme2 tcp traddr=127.0.0.2,trsvcid=4460,src_addr=127.0.0.1 live >>>    +- nvme2c3n1 optimized 3,4 0 nvme3 tcp traddr=127.0.0.3,trsvcid=4460,src_addr=127.0.0.1 live >>> >>> Please note that the annotations shown above (e.g., , >>> , , and ) are included for clarity >>> only and are not part of the actual output. >>> >> >> Hmm. Why do we have the values for 'numa-node-list' and 'queue-depth' >> both in here? They are tied to the selected IO policy, and pretty >> meaningless if that IO policy is not selected. >> Please include only the values relevant for the selected IO policy; >> this will increase readability of the resulting status string. >> > Okay makes sense, so we'd print and exclude if iopolicy > is numa. For 'queue-depth' iopolicy, we'd print and exclude . > And for 'round-robin' iopolicy, we'd neither print nor . > I'll update this in the next patch. > Hmm. I'd rather have _some_ value for 'round-robin', too, as otherwise the number of fields will be different (and making parsing harder). Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich