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Wed, 29 Apr 2026 07:15:29 +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 eapEFxGw8WkzAwAAD6G6ig (envelope-from ); Wed, 29 Apr 2026 07:15:29 +0000 Message-ID: <3a606788-bd88-4249-bf1c-b0f99cf680e3@suse.de> Date: Wed, 29 Apr 2026 09:15:28 +0200 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v12 05/13] blk-mq: add blk_mq_{online|possible}_queue_affinity To: Daniel Wagner , Sebastian Andrzej Siewior Cc: Aaron Tomlin , axboe@kernel.dk, kbusch@kernel.org, hch@lst.de, sagi@grimberg.me, mst@redhat.com, aacraid@microsemi.com, James.Bottomley@hansenpartnership.com, martin.petersen@oracle.com, liyihang9@h-partners.com, kashyap.desai@broadcom.com, sumit.saxena@broadcom.com, shivasharan.srikanteshwara@broadcom.com, chandrakanth.patil@broadcom.com, sathya.prakash@broadcom.com, sreekanth.reddy@broadcom.com, suganath-prabu.subramani@broadcom.com, ranjan.kumar@broadcom.com, jinpu.wang@cloud.ionos.com, tglx@kernel.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, akpm@linux-foundation.org, maz@kernel.org, ruanjinjie@huawei.com, yphbchou0911@gmail.com, wagi@kernel.org, frederic@kernel.org, longman@redhat.com, chenridong@huawei.com, kch@nvidia.com, ming.lei@redhat.com, tom.leiming@gmail.com, steve@abita.co, sean@ashe.io, chjohnst@gmail.com, neelx@suse.com, mproche@gmail.com, nick.lange@gmail.com, marco.crivellari@suse.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux.dev, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, megaraidlinux.pdl@broadcom.com, mpi3mr-linuxdrv.pdl@broadcom.com, MPT-FusionLinux.pdl@broadcom.com References: <20260422185215.100929-1-atomlin@atomlin.com> <20260422185215.100929-6-atomlin@atomlin.com> <20260427153416.MeVS8yxF@linutronix.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 [-6.80 / 50.00]; REPLY(-4.00)[]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-0.993]; MIME_GOOD(-0.10)[text/plain]; FUZZY_RATELIMITED(0.00)[rspamd.com]; TAGGED_RCPT(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_VIA_SMTP_AUTH(0.00)[]; URIBL_BLOCKED(0.00)[imap1.dmz-prg2.suse.org:helo,suse.de:mid,suse.de:email]; TO_DN_SOME(0.00)[]; RCVD_TLS_ALL(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[atomlin.com,kernel.dk,kernel.org,lst.de,grimberg.me,redhat.com,microsemi.com,hansenpartnership.com,oracle.com,h-partners.com,broadcom.com,cloud.ionos.com,infradead.org,linaro.org,linux-foundation.org,huawei.com,gmail.com,nvidia.com,abita.co,ashe.io,suse.com,vger.kernel.org,lists.linux.dev,lists.infradead.org]; R_RATELIMIT(0.00)[to_ip_from(RLxytqtu68cujj4wfi14kxder6)]; FROM_EQ_ENVFROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCPT_COUNT_GT_50(0.00)[52]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.de:mid,suse.de:email] X-Spam-Flag: NO X-Spam-Score: -6.80 X-Spam-Level: On 4/28/26 14:53, Daniel Wagner wrote: > On Mon, Apr 27, 2026 at 05:34:16PM +0200, Sebastian Andrzej Siewior wrote: >> Which driver uses cpu_possible_mask? This mask is assigned at boot time >> once the kernel figured how many CPUs are possible based on ACPI or >> whatever the system uses. This mask does not change. >> >> I only see drivers/scsi/lpfc/lpfc_init.c using it. Looking at >> cpu_possible_mask might not be the right thing. It is usually the same >> thing as "online" except on system where ACPI thinks that something >> could be added via hotplug _or_ if the admin shuts down a CPU via >> cpuhotplug _or_ boots with less (there a command line option for >> that). > > These HBAs are used on PowerPC which supports lpar (CPUs can be added > during runtime) I am told it's properly the only driver which is caring > about this type configuration, thus a bit of an odd ball. > >> In case cpu_possible_mask != cpu_online_mask the intention is to >> allocate memory and setup irqs for the offline CPUs? > > I can't answer this. The lpfc driver has several strategies implemented > how it spreads its resources. The intention is to setup the driver queue affinity only once (knowing that all possible CPUs are handled correctly), avoiding a driver reconfiguration on CPU hotplug. Not the most efficient one, sure. 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