From: Daniel Wagner <dwagner@suse.de>
To: Florian Bezdeka <florian.bezdeka@siemens.com>
Cc: Aaron Tomlin <atomlin@atomlin.com>,
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 <jan.kiszka@siemens.com>
Subject: Re: [PATCH v12 00/13] blk: honor isolcpus configuration
Date: Thu, 30 Apr 2026 14:09:21 +0200 [thread overview]
Message-ID: <8c074639-bb75-40be-a338-e80b93123477@flourine.local> (raw)
In-Reply-To: <85415539137c61cdec145ac0ee299dbea7cdd2a1.camel@siemens.com>
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.
next prev parent reply other threads:[~2026-04-30 12:09 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-22 18:52 [PATCH v12 00/13] blk: honor isolcpus configuration Aaron Tomlin
2026-04-22 18:52 ` [PATCH v12 01/13] scsi: aacraid: use block layer helpers to calculate num of queues Aaron Tomlin
2026-05-05 18:42 ` Aaron Tomlin
2026-04-22 18:52 ` [PATCH v12 02/13] lib/group_cpus: remove dead !SMP code Aaron Tomlin
2026-04-27 15:21 ` Sebastian Andrzej Siewior
2026-04-29 23:32 ` Aaron Tomlin
2026-04-22 18:52 ` [PATCH v12 03/13] lib/group_cpus: Add group_mask_cpus_evenly() Aaron Tomlin
2026-04-22 18:52 ` [PATCH v12 04/13] genirq/affinity: Add cpumask to struct irq_affinity Aaron Tomlin
2026-05-05 20:40 ` Aaron Tomlin
2026-04-22 18:52 ` [PATCH v12 05/13] blk-mq: add blk_mq_{online|possible}_queue_affinity Aaron Tomlin
2026-04-27 15:34 ` Sebastian Andrzej Siewior
2026-04-28 12:53 ` Daniel Wagner
2026-04-29 7:15 ` Hannes Reinecke
2026-05-05 20:55 ` Aaron Tomlin
2026-04-22 18:52 ` [PATCH v12 06/13] nvme-pci: use block layer helpers to constrain queue affinity Aaron Tomlin
2026-05-05 19:47 ` Aaron Tomlin
2026-04-22 18:52 ` [PATCH v12 07/13] scsi: Use " Aaron Tomlin
2026-04-22 18:52 ` [PATCH v12 08/13] virtio: blk/scsi: use " Aaron Tomlin
2026-04-22 18:52 ` [PATCH v12 09/13] isolation: Introduce io_queue isolcpus type Aaron Tomlin
2026-04-22 18:52 ` [PATCH v12 10/13] blk-mq: use hk cpus only when isolcpus=io_queue is enabled Aaron Tomlin
2026-05-02 21:25 ` Aaron Tomlin
2026-04-22 18:52 ` [PATCH v12 11/13] blk-mq: prevent offlining hk CPUs with associated online isolated CPUs Aaron Tomlin
2026-04-22 18:52 ` [PATCH v12 12/13] genirq/affinity: Restrict managed IRQ affinity to housekeeping CPUs Aaron Tomlin
2026-04-22 18:52 ` [PATCH v12 13/13] docs: add io_queue flag to isolcpus Aaron Tomlin
2026-04-27 10:55 ` [PATCH v12 00/13] blk: honor isolcpus configuration Florian Bezdeka
2026-04-28 13:08 ` Daniel Wagner
2026-04-29 21:01 ` Florian Bezdeka
2026-04-30 12:09 ` Daniel Wagner [this message]
2026-04-30 15:45 ` Jan Kiszka
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