[PATCH v3 08/15] sched/isolation: Add io_queue housekeeping option

[Daniel Wagner]

Multiqueue drivers such as nvme-pci are spreading IO queues on all CPUs
for optimal performance. isolcpu users are usually more concerned about
noise on isolated CPUs. Introduce a new isolcpus mask which allows the
user to define on which CPUs IO queues should be placed.

Signed-off-by: Daniel Wagner <dwag...@suse.de>
---
 include/linux/sched/isolation.h | 15 +++++++++++++++
 kernel/sched/isolation.c        |  7 +++++++
 2 files changed, 22 insertions(+)

diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index 2b461129d1fa..0101d0fc8c00 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -6,6 +6,20 @@
 #include <linux/init.h>
 #include <linux/tick.h>
 
+/**
+ * enum hk_type - housekeeping cpu mask types
+ * @HK_TYPE_TIMER:     housekeeping cpu mask for timers
+ * @HK_TYPE_RCU:       housekeeping cpu mask for RCU
+ * @HK_TYPE_MISC:      housekeeping cpu mask for miscalleanous resources
+ * @HK_TYPE_SCHED:     housekeeping cpu mask for scheduling
+ * @HK_TYPE_TICK:      housekeeping cpu maks for timer tick
+ * @HK_TYPE_DOMAIN:    housekeeping cpu mask for general SMP balancing
+ *                     and scheduling algoririthms
+ * @HK_TYPE_WQ:                housekeeping cpu mask for worksqueues
+ * @HK_TYPE_MANAGED_IRQ: housekeeping cpu mask for managed IRQs
+ * @HK_TYPE_KTHREAD:   housekeeping cpu mask for kthreads
+ * @HK_TYPE_IO_QUEUE:  housekeeping cpu mask for I/O queues
+ */
 enum hk_type {
        HK_TYPE_TIMER,
        HK_TYPE_RCU,
@@ -16,6 +30,7 @@ enum hk_type {
        HK_TYPE_WQ,
        HK_TYPE_MANAGED_IRQ,
        HK_TYPE_KTHREAD,
+       HK_TYPE_IO_QUEUE,
        HK_TYPE_MAX
 };
 
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 5891e715f00d..91d7a434330c 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -18,6 +18,7 @@ enum hk_flags {
        HK_FLAG_WQ              = BIT(HK_TYPE_WQ),
        HK_FLAG_MANAGED_IRQ     = BIT(HK_TYPE_MANAGED_IRQ),
        HK_FLAG_KTHREAD         = BIT(HK_TYPE_KTHREAD),
+       HK_FLAG_IO_QUEUE        = BIT(HK_TYPE_IO_QUEUE),
 };
 
 DEFINE_STATIC_KEY_FALSE(housekeeping_overridden);
@@ -228,6 +229,12 @@ 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.

-- 
2.46.0