[PATCH v9 09/13] isolation: Introduce io_queue isolcpus type

Aaron Tomlin
2026-03-31T06:26:07Z

From: Daniel Wagner <wagi@kernel.org>

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@suse.de>
Reviewed-by: Aaron Tomlin <atomlin@atomlin.com>
Signed-off-by: Daniel Wagner <wagi@kernel.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 dc3975ff1b2e..7b266fc2a405 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -18,6 +18,7 @@ enum hk_type {
HK_TYPE_MANAGED_IRQ,
/* Inverse of boot-time nohz_full= or isolcpus=nohz arguments */
HK_TYPE_KERNEL_NOISE,
+ HK_TYPE_IO_QUEUE,
HK_TYPE_MAX,

/*
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index ef152d401fe2..3406e3024fd4 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -16,6 +16,7 @@ enum hk_flags {
HK_FLAG_DOMAIN = BIT(HK_TYPE_DOMAIN),
HK_FLAG_MANAGED_IRQ = BIT(HK_TYPE_MANAGED_IRQ),
HK_FLAG_KERNEL_NOISE = BIT(HK_TYPE_KERNEL_NOISE),
+ HK_FLAG_IO_QUEUE = BIT(HK_TYPE_IO_QUEUE),
};

DEFINE_STATIC_KEY_FALSE(housekeeping_overridden);
@@ -340,6 +341,12 @@ 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