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Mon, 2 Nov 2026 07:26:58 +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 UBfCAEI76GpfbQAAD6G6ig (envelope-from ); Mon, 02 Nov 2026 07:26:58 +0000 Message-ID: <6e9e6f78-4bd7-46f0-bf57-5c227a65a69e@suse.de> Date: Mon, 2 Nov 2026 08:26:57 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] nvme: remove namespaces in parallel To: Qiliang Yuan , Keith Busch , Jens Axboe , Christoph Hellwig , Sagi Grimberg Cc: linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, Ming Lei , Nilay Shroff , Shin'ichiro Kawasaki , Stuart Hayes References: <20261102-bug-nvme-remove-ns-async-v1-0-61780fee111c@gmail.com> <20261102-bug-nvme-remove-ns-async-v1-1-61780fee111c@gmail.com> Content-Language: en-US From: Hannes Reinecke In-Reply-To: <20261102-bug-nvme-remove-ns-async-v1-1-61780fee111c@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Spamd-Result: default: False [-11.79 / 50.00]; SUSE_INTERNAL_BYPASS(-9.00)[]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; XM_UA_NO_VERSION(0.01)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FREEMAIL_TO(0.00)[gmail.com,kernel.org,kernel.dk,lst.de,grimberg.me]; ARC_NA(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; RCPT_COUNT_TWELVE(0.00)[12]; MIME_TRACE(0.00)[0:+]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; RCVD_TLS_ALL(0.00)[]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[lists.infradead.org,vger.kernel.org,gmail.com,linux.ibm.com,wdc.com]; RCVD_COUNT_TWO(0.00)[2]; TAGGED_RCPT(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.de:email] X-Spam-Score: -11.79 X-Spam-Level: X-Spam-Flag: NO On 11/2/26 7:14 AM, Qiliang Yuan wrote: > nvme_remove_namespaces() removes the namespaces of a controller one > after another. Each removal waits for RCU grace periods in > del_gendisk() for the namespace and for its multipath head, about > 20 ms in all. > But that isn't changed by calling async_schedule_domain, isn't it? > Deleting a controller, such as disconnecting from a fabrics target, > thus takes time proportional to its namespace count, over a second for > 64 namespaces. Scanning had the same problem until commit 4e893ca81170 > ("nvme_core: scan namespaces asynchronously") made it add namespaces > in parallel. > > Remove the namespaces through an async domain the same way, and wait > for all of them before returning. > > Disconnect time from a target on the same host, over tcp to 127.0.0.1 > and over nvme-loop, with 4 I/O queues, median of 3 runs on each of two > boots per kernel: > > namespaces transport before after > 8 tcp 170 / 171 ms 85 / 91 ms > 32 tcp 628 / 628 ms 294 / 293 ms > 64 tcp 1201 / 1308 ms 533 / 550 ms > 64 loop 1988 / 1913 ms 1283 / 1200 ms > > Signed-off-by: Qiliang Yuan > --- > drivers/nvme/host/core.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) > > diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c > index a7a4d09644c13..18948c2ba218d 100644 > --- a/drivers/nvme/host/core.c > +++ b/drivers/nvme/host/core.c > @@ -4716,6 +4716,11 @@ static void nvme_scan_work(struct work_struct *work) > #endif > } > > +static void nvme_ns_remove_async(void *data, async_cookie_t cookie) > +{ > + nvme_ns_remove(data); > +} > + > /* > * This function iterates the namespace list unlocked to allow recovery from > * controller failure. It is up to the caller to ensure the namespace list is > @@ -4725,6 +4730,7 @@ void nvme_remove_namespaces(struct nvme_ctrl *ctrl) > { > struct nvme_ns *ns, *next; > LIST_HEAD(ns_list); > + ASYNC_DOMAIN(domain); > > /* > * make sure to requeue I/O to all namespaces as these > @@ -4759,8 +4765,13 @@ void nvme_remove_namespaces(struct nvme_ctrl *ctrl) > mutex_unlock(&ctrl->namespaces_lock); > synchronize_srcu(&ctrl->srcu); > > + /* > + * Remove the namespaces in parallel, as each removal waits for several > + * RCU grace periods. > + */ > list_for_each_entry_safe(ns, next, &ns_list, list) > - nvme_ns_remove(ns); > + async_schedule_domain(nvme_ns_remove_async, ns, &domain); > + async_synchronize_full_domain(&domain); > } > EXPORT_SYMBOL_GPL(nvme_remove_namespaces); > > Other than that it looks fine. 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