linux-kernel - [PATCH v8 09/12] isolation: Introduce io

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Message-Id: <20250905-isolcpus-io-queues-v8-9-885984c5daca@kernel.org>
Date: Fri, 05 Sep 2025 16:59:55 +0200
From: Daniel Wagner <wagi@...nel.org>
To: Jens Axboe <axboe@...nel.dk>, Keith Busch <kbusch@...nel.org>, 
 Christoph Hellwig <hch@....de>, Sagi Grimberg <sagi@...mberg.me>, 
 "Michael S. Tsirkin" <mst@...hat.com>
Cc: Aaron Tomlin <atomlin@...mlin.com>, 
 "Martin K. Petersen" <martin.petersen@...cle.com>, 
 Thomas Gleixner <tglx@...utronix.de>, 
 Costa Shulyupin <costa.shul@...hat.com>, Juri Lelli <juri.lelli@...hat.com>, 
 Valentin Schneider <vschneid@...hat.com>, Waiman Long <llong@...hat.com>, 
 Ming Lei <ming.lei@...hat.com>, Frederic Weisbecker <frederic@...nel.org>, 
 Mel Gorman <mgorman@...e.de>, Hannes Reinecke <hare@...e.de>, 
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, 
 Aaron Tomlin <atomlin@...mlin.com>, linux-kernel@...r.kernel.org, 
 linux-block@...r.kernel.org, linux-nvme@...ts.infradead.org, 
 megaraidlinux.pdl@...adcom.com, linux-scsi@...r.kernel.org, 
 storagedev@...rochip.com, virtualization@...ts.linux.dev, 
 GR-QLogic-Storage-Upstream@...vell.com, Daniel Wagner <wagi@...nel.org>
Subject: [PATCH v8 09/12] isolation: Introduce io_queue isolcpus type

Multiqueue drivers spread I/O queues across all CPUs for optimal
performance. However, these drivers are not aware of CPU isolation
requirements and will distribute queues without considering the isolcpus
configuration.

Introduce a new isolcpus mask that allows users to define which CPUs
should have I/O queues assigned. This is similar to managed_irq, but
intended for drivers that do not use the managed IRQ infrastructure

Reviewed-by: Hannes Reinecke <hare@...e.de>
Reviewed-by: Aaron Tomlin <atomlin@...mlin.com>
Signed-off-by: Daniel Wagner <wagi@...nel.org>
---
 include/linux/sched/isolation.h | 1 +
 kernel/sched/isolation.c        | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index d8501f4709b583b8a1c91574446382f093bccdb1..6b6ae9c5b2f61a93c649a98ea27482b932627fca 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -9,6 +9,7 @@
 enum hk_type {
 	HK_TYPE_DOMAIN,
 	HK_TYPE_MANAGED_IRQ,
+	HK_TYPE_IO_QUEUE,
 	HK_TYPE_KERNEL_NOISE,
 	HK_TYPE_MAX,

diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index a4cf17b1fab062f536c7f4f47c35f0e209fd25d6..0d59cc95bf3b8fa2f06cb562ce1baf3fdd48c9db 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -13,6 +13,7 @@
 enum hk_flags {
 	HK_FLAG_DOMAIN		= BIT(HK_TYPE_DOMAIN),
 	HK_FLAG_MANAGED_IRQ	= BIT(HK_TYPE_MANAGED_IRQ),
+	HK_FLAG_IO_QUEUE	= BIT(HK_TYPE_IO_QUEUE),
 	HK_FLAG_KERNEL_NOISE	= BIT(HK_TYPE_KERNEL_NOISE),
 };

@@ -226,6 +227,12 @@ static int __init housekeeping_isolcpus_setup(char *str)
 			continue;
 		}

+		if (!strncmp(str, "io_queue,", 9)) {
+			str += 9;
+			flags |= HK_FLAG_IO_QUEUE;
+			continue;
+		}
+
 		/*
 		 * Skip unknown sub-parameter and validate that it is not
 		 * containing an invalid character.

-- 
2.51.0