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Thu, 30 Apr 2026 12:09:22 +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 /0o+GHJG82kjZQAAD6G6ig (envelope-from ); Thu, 30 Apr 2026 12:09:22 +0000 Date: Thu, 30 Apr 2026 14:09:21 +0200 From: Daniel Wagner To: Florian Bezdeka 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, bigeasy@linutronix.de, yphbchou0911@gmail.com, wagi@kernel.org, frederic@kernel.org, longman@redhat.com, chenridong@huawei.com, hare@suse.de, 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, Jan Kiszka Subject: Re: [PATCH v12 00/13] blk: honor isolcpus configuration Message-ID: <8c074639-bb75-40be-a338-e80b93123477@flourine.local> References: <20260422185215.100929-1-atomlin@atomlin.com> <2d61b1f7-fc06-4fe1-8a6f-cc3a2f114ae1@flourine.local> <85415539137c61cdec145ac0ee299dbea7cdd2a1.camel@siemens.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <85415539137c61cdec145ac0ee299dbea7cdd2a1.camel@siemens.com> X-Spamd-Result: default: False [-3.01 / 50.00]; BAYES_HAM(-3.00)[99.99%]; SUSPICIOUS_RECIPS(1.50)[]; 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)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; TO_DN_SOME(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; MIME_TRACE(0.00)[0:+]; ARC_NA(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,linutronix.de,gmail.com,suse.de,nvidia.com,abita.co,ashe.io,suse.com,vger.kernel.org,lists.linux.dev,lists.infradead.org,siemens.com]; DKIM_TRACE(0.00)[suse.de:+]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; TO_MATCH_ENVRCPT_SOME(0.00)[]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; RCVD_TLS_ALL(0.00)[]; RCPT_COUNT_GT_50(0.00)[54]; TAGGED_RCPT(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; MISSING_XM_UA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:dkim,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns] X-Rspamd-Action: no action X-Spam-Flag: NO X-Spam-Score: -3.01 X-Spam-Level: X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Rspamd-Queue-Id: 838016A81C On Wed, Apr 29, 2026 at 11:01:33PM +0200, Florian Bezdeka wrote: > > Which use case are you actually aiming to support? While dynamic > > reconfiguration would be ideal, the amount of work to get there is > > significant. I won't be signing up for it. > > The use case at hand is a RT enabled platform where the concrete RT > workload is not known at boot time. RT applications are deployed "on- > the-fly", nowadays using the existing container runtimes with some > extended resource management on top. > > Applications can request certain resources like isolated CPU cores, > special IRQ affinities, PCI devices to pass through, ..., so that the > resource management on the system can take care of proper system > configuration. This is where I really question this use case. Currently, it takes quite a lot of time to tune a system to work properly for RT workloads. Between memory channel interference, GPU interference, and shared transports everywhere, you end up with a fixed split: a set of CPUs suitable for RT work and a set for housekeeping. This partitioning generally does not change during runtime, even if the way you utilize those two sets remains dynamic. Furthermore, reconfiguring a system while running an active RT workload is asking for trouble. I wouldn't be surprised if doing so triggered a wide range of unpredictable side effects.