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>,
"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>,
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 v5 8/9] blk-mq: issue warning when offlining hctx with online isolcpus
Date: Sat, 11 Jan 2025 11:40:39 +0800 [thread overview]
Message-ID: <Z4HoN0F0cKD5G16F@fedora> (raw)
In-Reply-To: <20250110-isolcpus-io-queues-v5-8-0e4f118680b0@kernel.org>
Hi Daniel,
On Fri, Jan 10, 2025 at 05:26:46PM +0100, Daniel Wagner wrote:
> When isolcpus=managed_irq is enabled, and the last housekeeping CPU for
> a given hardware context goes offline, there is no CPU left which
> handles the IOs anymore. If isolated CPUs mapped to this hardware
> context are online and an application running on these isolated CPUs
> issue an IO this will lead to stalls.
>
> The kernel will not schedule IO to isolated CPUS thus this avoids IO
> stalls.
>
> Thus issue a warning when housekeeping CPUs are offlined for a hardware
> context while there are still isolated CPUs online.
Why do you continue to send patch without addressing the fundamental regression?
This patchset does break existed applications which can't follow the new
rule of offlining CPU in order.
Again, it violates no-regression rule of kernel development.
Thanks,
Ming
next prev parent reply other threads:[~2025-01-11 3:41 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-10 16:26 [PATCH v5 0/9] blk: honor isolcpus configuration Daniel Wagner
2025-01-10 16:26 ` [PATCH v5 1/9] lib/group_cpus: let group_cpu_evenly return number initialized masks Daniel Wagner
2025-01-13 7:07 ` Hannes Reinecke
2025-01-10 16:26 ` [PATCH v5 2/9] blk-mq: add number of queue calc helper Daniel Wagner
2025-01-10 16:26 ` [PATCH v5 3/9] nvme-pci: use block layer helpers to calculate num of queues Daniel Wagner
2025-01-10 16:26 ` [PATCH v5 4/9] scsi: " Daniel Wagner
2025-01-10 21:37 ` Martin K. Petersen
2025-01-13 7:10 ` Hannes Reinecke
2025-01-10 16:26 ` [PATCH v5 5/9] virtio: blk/scsi: " Daniel Wagner
2025-01-13 7:11 ` Hannes Reinecke
2025-01-10 16:26 ` [PATCH v5 6/9] lib/group_cpus: honor housekeeping config when grouping CPUs Daniel Wagner
2025-01-10 16:26 ` [PATCH v5 7/9] blk-mq: use hk cpus only when isolcpus=managed_irq is enabled Daniel Wagner
2025-01-13 7:13 ` Hannes Reinecke
2025-01-10 16:26 ` [PATCH v5 8/9] blk-mq: issue warning when offlining hctx with online isolcpus Daniel Wagner
2025-01-11 3:40 ` Ming Lei [this message]
2025-01-13 7:14 ` Hannes Reinecke
2025-01-10 16:26 ` [PATCH v5 9/9] doc: update managed_irq documentation Daniel Wagner
2025-01-13 7:14 ` Hannes Reinecke
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