hv: sched_iorr: Add IO sensitive Round-robin scheduler

IO sensitive Round-robin scheduler aim to schedule threads with
round-robin policy. Meanwhile, we also enhance it with some fairness
configuration, such as thread will be scheduled out without properly
timeslice. IO request on thread will be handled in high priority.

This patch only add a skeleton for the sched_iorr scheduler.

Tracked-On: #4178
Signed-off-by: Jason Chen CJ <jason.cj.chen@intel.com>
Signed-off-by: Yu Wang <yu1.wang@intel.com>
Signed-off-by: Shuo A Liu <shuo.a.liu@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

hypervisor/common/sched_iorr.c

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2019 Intel Corporation. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <list.h>
+#include <per_cpu.h>
+#include <schedule.h>
+
+struct sched_iorr_data {
+	/* keep list as the first item */
+	struct list_head list;
+
+	uint64_t slice_cycles;
+	uint64_t last_cycles;
+	int64_t  left_cycles;
+};
+
+int sched_iorr_init(__unused struct sched_control *ctl)
+{
+	return 0;
+}
+
+void sched_iorr_deinit(__unused struct sched_control *ctl)
+{
+}
+
+void sched_iorr_init_data(__unused struct thread_object *obj)
+{
+}
+
+static struct thread_object *sched_iorr_pick_next(__unused struct sched_control *ctl)
+{
+	return NULL;
+}
+
+static void sched_iorr_sleep(__unused struct thread_object *obj)
+{
+}
+
+static void sched_iorr_wake(__unused struct thread_object *obj)
+{
+}
+
+struct acrn_scheduler sched_iorr = {
+	.name		= "sched_iorr",
+	.init		= sched_iorr_init,
+	.init_data	= sched_iorr_init_data,
+	.pick_next	= sched_iorr_pick_next,
+	.sleep		= sched_iorr_sleep,
+	.wake		= sched_iorr_wake,
+	.deinit		= sched_iorr_deinit,
+};