[PATCH v13 4/8] isolation: Introduce io_queue isolcpus type

[Aaron Tomlin <atomlin@atomlin.com>]

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

Signed-off-by: Daniel Wagner <wagi@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Aaron Tomlin <atomlin@atomlin.com>
---
 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 cf0fd03dd7a2..30cb9a44365e 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