event: define scheduler API

Add structures and function for new scheduler API.

Change-Id: I8e379db62189eb7c36092265c137f07368650e9b
Signed-off-by: Vitaliy Mysak <vitaliy.mysak@intel.com>
Signed-off-by: Maciej Szwed <maciej.szwed@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/4053
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Aleksey Marchuk <alexeymar@mellanox.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>

include/spdk_internal/event.h

@@ -62,8 +62,11 @@ enum spdk_reactor_state {
 
 struct spdk_lw_thread {
 	TAILQ_ENTRY(spdk_lw_thread)	link;
-	bool				resched;
 	uint64_t			tsc_start;
+	uint32_t                        lcore;
+	uint32_t                        new_lcore;
+	bool				resched;
+	struct spdk_thread_stats        current_stats;
 };
 
 struct spdk_reactor {
@@ -76,7 +79,8 @@ struct spdk_reactor {
 
 	struct {
 		uint32_t				is_valid : 1;
-		uint32_t				reserved : 31;
+		uint32_t				is_scheduling : 1;
+		uint32_t				reserved : 30;
 	} flags;
 
 	uint64_t					tsc_last;
@@ -171,6 +175,79 @@ void spdk_subsystem_config_json(struct spdk_json_write_ctx *w, struct spdk_subsy
 void spdk_rpc_initialize(const char *listen_addr);
 void spdk_rpc_finish(void);
 
+/**
+ * A list of cores and threads which is used for scheduling.
+ */
+struct spdk_scheduler_core_info {
+	uint64_t core_idle_tsc;
+	uint64_t core_busy_tsc;
+	uint32_t lcore;
+	uint32_t threads_count;
+	struct spdk_lw_thread **threads;
+};
+
+/**
+ * Scheduler balance function type.
+ * Accepts array of core_info which is of size 'count' and returns updated array.
+ */
+typedef void (*spdk_scheduler_balance_fn)(struct spdk_scheduler_core_info *core_info, int count);
+
+/**
+ * Scheduler init function type.
+ * Called on scheduler module initialization.
+ */
+typedef int (*spdk_scheduler_init_fn)(void);
+
+/**
+ * Scheduler deinitialization function type.
+ * Called on reactor fini.
+ */
+typedef int (*spdk_scheduler_deinit_fn)(void);
+
+/** Thread scheduler */
+struct spdk_scheduler {
+	char                        *name;
+	spdk_scheduler_init_fn       init;
+	spdk_scheduler_deinit_fn     deinit;
+	spdk_scheduler_balance_fn    balance;
+	TAILQ_ENTRY(spdk_scheduler)  link;
+};
+
+/**
+ * Add the given scheduler to the list of registered schedulers.
+ * This function should be invoked by referencing the macro
+ * SPDK_SCHEDULER_REGISTER in the scheduler c file.
+ *
+ * \param scheduler Scheduler to be added.
+ */
+void _spdk_scheduler_list_add(struct spdk_scheduler *scheduler);
+
+/**
+ * Change current scheduler.
+ *
+ * \param name Name of the scheduler to be used.
+ *
+ * \return 0 on success or non-zero on failure.
+ */
+int _spdk_scheduler_set(char *name);
+
+/**
+ * Change current scheduling period.
+ *
+ * \param period New period (ticks).
+ *               Use spdk_get_ticks_hz() to translate seconds to ticks.
+ */
+void _spdk_scheduler_period_set(uint32_t period);
+
+/*
+ * Macro used to register new reactor balancer.
+ */
+#define SPDK_SCHEDULER_REGISTER(scheduler) \
+static void __attribute__((constructor)) _spdk_scheduler_register_##name(void) \
+{ \
+	spdk_scheduler_list_add(scheduler); \
+} \
+
 /**
  * \brief Register a new subsystem
  */

lib/event/reactor.c

@@ -62,9 +62,61 @@ static bool g_framework_context_switch_monitor_enabled = true;
 
 static struct spdk_mempool *g_spdk_event_mempool = NULL;
 
+TAILQ_HEAD(, spdk_scheduler) g_scheduler_list
+	= TAILQ_HEAD_INITIALIZER(g_scheduler_list);
+
+static struct spdk_scheduler *g_scheduler;
+static uint32_t g_scheduler_period;
+
 static int reactor_interrupt_init(struct spdk_reactor *reactor);
 static void reactor_interrupt_fini(struct spdk_reactor *reactor);
 
+static struct spdk_scheduler *
+_scheduler_find(char *name)
+{
+	struct spdk_scheduler *tmp;
+
+	TAILQ_FOREACH(tmp, &g_scheduler_list, link) {
+		if (strcmp(name, tmp->name) == 0) {
+			return tmp;
+		}
+	}
+
+	return NULL;
+}
+
+int
+_spdk_scheduler_set(char *name)
+{
+	struct spdk_scheduler *scheduler;
+
+	scheduler = _scheduler_find(name);
+	if (scheduler == NULL) {
+		return -ENOENT;
+	}
+
+	g_scheduler = scheduler;
+	return 0;
+}
+
+void
+_spdk_scheduler_period_set(uint32_t period)
+{
+	g_scheduler_period = period;
+}
+
+void
+_spdk_scheduler_list_add(struct spdk_scheduler *scheduler)
+{
+	if (_scheduler_find(scheduler->name)) {
+		SPDK_ERRLOG("scheduler named '%s' already registered.\n", scheduler->name);
+		assert(false);
+		return;
+	}
+
+	TAILQ_INSERT_TAIL(&g_scheduler_list, scheduler, link);
+}
+
 static void
 reactor_construct(struct spdk_reactor *reactor, uint32_t lcore)
 {
@@ -689,6 +741,7 @@ _reactor_request_thread_reschedule(struct spdk_thread *thread)
 	assert(lw_thread != NULL);
 
 	lw_thread->resched = true;
+	lw_thread->lcore = SPDK_ENV_LCORE_ID_ANY;
 
 	current_core = spdk_env_get_current_core();
 	reactor = spdk_reactor_get(current_core);