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From: Ming Lei <ming.lei@redhat.com>
To: Daniel Wagner <wagi@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>, Keith Busch <kbusch@kernel.org>,
	Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Aaron Tomlin <atomlin@atomlin.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Costa Shulyupin <costa.shul@redhat.com>,
	Juri Lelli <juri.lelli@redhat.com>,
	Valentin Schneider <vschneid@redhat.com>,
	Waiman Long <llong@redhat.com>,
	Frederic Weisbecker <frederic@kernel.org>,
	Mel Gorman <mgorman@suse.de>, Hannes Reinecke <hare@suse.de>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
	linux-nvme@lists.infradead.org, megaraidlinux.pdl@broadcom.com,
	linux-scsi@vger.kernel.org, storagedev@microchip.com,
	virtualization@lists.linux.dev,
	GR-QLogic-Storage-Upstream@marvell.com
Subject: Re: [PATCH v7 09/10] blk-mq: prevent offlining hk CPUs with associated online isolated CPUs
Date: Mon, 7 Jul 2025 15:44:30 +0800	[thread overview]
Message-ID: <aGt63lJr2JY8VAqc@fedora> (raw)
In-Reply-To: <20250702-isolcpus-io-queues-v7-9-557aa7eacce4@kernel.org>

On Wed, Jul 02, 2025 at 06:33:59PM +0200, Daniel Wagner wrote:
> When isolcpus=io_queue is enabled, and the last housekeeping CPU for a
> given hctx goes offline, there would be no CPU left to handle I/O. To
> prevent I/O stalls, prevent offlining housekeeping CPUs that are still
> serving isolated CPUs.
> 
> When isolcpus=io_queue is enabled and the last housekeeping CPU
> for a given hctx goes offline, no CPU would be left to handle I/O.
> To prevent I/O stalls, disallow offlining housekeeping CPUs that are
> still serving isolated CPUs.

If you do so, cpu offline is failed, and this change is user visible, please
document the cpu offline failure limit on Documentation/admin-guide/kernel-parameters.txt.
in the next patch.

Thanks,
Ming


  parent reply	other threads:[~2025-07-07  7:44 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-02 16:33 [PATCH v7 00/10] blk: honor isolcpus configuration Daniel Wagner
2025-07-02 16:33 ` [PATCH v7 01/10] lib/group_cpus: Add group_masks_cpus_evenly() Daniel Wagner
2025-07-03  6:18   ` Hannes Reinecke
2025-09-03 12:36     ` Daniel Wagner
2025-07-11  8:28   ` John Garry
2025-09-03 12:42     ` Daniel Wagner
2025-07-02 16:33 ` [PATCH v7 02/10] genirq/affinity: Add cpumask to struct irq_affinity Daniel Wagner
2025-07-03  6:19   ` Hannes Reinecke
2025-07-02 16:33 ` [PATCH v7 03/10] blk-mq: add blk_mq_{online|possible}_queue_affinity Daniel Wagner
2025-07-03  6:29   ` Hannes Reinecke
2025-07-02 16:33 ` [PATCH v7 04/10] nvme-pci: use block layer helpers to constrain queue affinity Daniel Wagner
2025-07-03  6:29   ` Hannes Reinecke
2025-07-02 16:33 ` [PATCH v7 05/10] scsi: Use " Daniel Wagner
2025-07-03  6:43   ` Hannes Reinecke
2025-07-04  9:37     ` Daniel Wagner
2025-07-04 10:28       ` Hannes Reinecke
2025-07-04 12:30         ` Daniel Wagner
2025-09-05  7:41     ` Daniel Wagner
2025-07-02 16:33 ` [PATCH v7 06/10] virtio: blk/scsi: use " Daniel Wagner
2025-07-03  6:43   ` Hannes Reinecke
2025-07-02 16:33 ` [PATCH v7 07/10] isolation: Introduce io_queue isolcpus type Daniel Wagner
2025-07-08  1:26   ` Aaron Tomlin
2025-07-02 16:33 ` [PATCH v7 08/10] blk-mq: use hk cpus only when isolcpus=io_queue is enabled Daniel Wagner
2025-07-03  6:58   ` Hannes Reinecke
2025-07-04  9:21     ` Daniel Wagner
2025-07-03  9:01   ` Christoph Hellwig
2025-07-04  9:00     ` Daniel Wagner
2025-07-07  5:42       ` Christoph Hellwig
2025-07-03 14:47   ` kernel test robot
2025-07-02 16:33 ` [PATCH v7 09/10] blk-mq: prevent offlining hk CPUs with associated online isolated CPUs Daniel Wagner
2025-07-03  6:58   ` Hannes Reinecke
2025-07-07  7:44   ` Ming Lei [this message]
2025-07-08  1:31     ` Aaron Tomlin
2025-07-08  1:23   ` Aaron Tomlin
2025-07-02 16:34 ` [PATCH v7 10/10] docs: add io_queue flag to isolcpus Daniel Wagner
2025-07-03  6:59   ` Hannes Reinecke
2025-07-08  1:26   ` Aaron Tomlin

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