reactor: add context_switch_monitor RPC

This allows the user to enable/disable getrusage() monitoring at
runtime.

Also change the log level to INFO and enable the monitoring in all
builds, not just #ifdef DEBUG.

Change-Id: I2f5c3bc8cd83dcb2a72dc7078bf2cb43aa28827c
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-on: https://review.gerrithub.io/376473
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Cunyin Chang <cunyin.chang@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>

include/spdk/event.h

@@ -176,4 +176,14 @@ void spdk_poller_register(struct spdk_poller **ppoller,
 void spdk_poller_unregister(struct spdk_poller **ppoller,
 			    struct spdk_event *complete);
 
+/**
+ * \brief Enable or disable monitoring of context switches.
+ */
+void spdk_reactor_enable_context_switch_monitor(bool enabled);
+
+/**
+ * \brief Return whether context switch monitoring is enabled.
+ */
+bool spdk_reactor_context_switch_monitor_enabled(void);
+
 #endif

lib/event/reactor.c

@@ -87,13 +87,13 @@ struct spdk_reactor {
 
 	/* Socket ID for this reactor. */
 	uint32_t					socket_id;
-#ifdef DEBUG
+
 	/* Poller for get the rusage for the reactor. */
 	struct spdk_poller				*rusage_poller;
 
 	/* The last known rusage values */
 	struct rusage 					rusage;
-#endif
+
 	/*
 	 * Contains pollers actively running on this reactor.  Pollers
 	 *  are run round-robin. The reactor takes one poller from the head
@@ -119,6 +119,8 @@ static struct spdk_reactor g_reactors[SPDK_MAX_REACTORS];
 
 static enum spdk_reactor_state	g_reactor_state = SPDK_REACTOR_STATE_INVALID;
 
+static bool g_context_switch_monitor_enabled = true;
+
 static void spdk_reactor_construct(struct spdk_reactor *w, uint32_t lcore,
 				   uint64_t max_delay_us);
 
@@ -254,7 +256,6 @@ _spdk_reactor_send_msg(spdk_thread_fn fn, void *ctx, void *thread_ctx)
 	spdk_event_call(event);
 }
 
-#ifdef DEBUG
 static void
 get_rusage(void *arg)
 {
@@ -266,14 +267,61 @@ get_rusage(void *arg)
 	}
 
 	if (rusage.ru_nvcsw != reactor->rusage.ru_nvcsw || rusage.ru_nivcsw != reactor->rusage.ru_nivcsw) {
-		SPDK_DEBUGLOG(SPDK_TRACE_REACTOR,
-			      "Reactor %d: %ld voluntary context switches and  %ld involuntary context switches in the last second.\n",
-			      reactor->lcore, rusage.ru_nvcsw - reactor->rusage.ru_nvcsw,
-			      rusage.ru_nivcsw - reactor->rusage.ru_nivcsw);
+		SPDK_INFOLOG(SPDK_TRACE_REACTOR,
+			     "Reactor %d: %ld voluntary context switches and %ld involuntary context switches in the last second.\n",
+			     reactor->lcore, rusage.ru_nvcsw - reactor->rusage.ru_nvcsw,
+			     rusage.ru_nivcsw - reactor->rusage.ru_nivcsw);
 	}
 	reactor->rusage = rusage;
 }
-#endif
+
+static void
+_spdk_reactor_context_switch_monitor_start(void *arg1, void *arg2)
+{
+	struct spdk_reactor *reactor = arg1;
+
+	if (reactor->rusage_poller == NULL) {
+		getrusage(RUSAGE_THREAD, &reactor->rusage);
+		spdk_poller_register(&reactor->rusage_poller, get_rusage, reactor, reactor->lcore, 1000000);
+	}
+}
+
+static void
+_spdk_reactor_context_switch_monitor_stop(void *arg1, void *arg2)
+{
+	struct spdk_reactor *reactor = arg1;
+
+	if (reactor->rusage_poller != NULL) {
+		spdk_poller_unregister(&reactor->rusage_poller, NULL);
+	}
+}
+
+void
+spdk_reactor_enable_context_switch_monitor(bool enable)
+{
+	struct spdk_reactor *reactor;
+	spdk_event_fn fn;
+	uint32_t core;
+
+	if (enable != g_context_switch_monitor_enabled) {
+		g_context_switch_monitor_enabled = enable;
+		if (enable) {
+			fn = _spdk_reactor_context_switch_monitor_start;
+		} else {
+			fn = _spdk_reactor_context_switch_monitor_stop;
+		}
+		SPDK_ENV_FOREACH_CORE(core) {
+			reactor = spdk_reactor_get(core);
+			spdk_event_call(spdk_event_allocate(core, fn, reactor, NULL));
+		}
+	}
+}
+
+bool
+spdk_reactor_context_switch_monitor_enabled(void)
+{
+	return g_context_switch_monitor_enabled;
+}
 
 /**
  *
@@ -317,10 +365,9 @@ _spdk_reactor_run(void *arg)
 	sleep_cycles = reactor->max_delay_us * spdk_get_ticks_hz() / 1000000ULL;
 	idle_started = 0;
 	timer_poll_count = 0;
-#ifdef DEBUG
-	getrusage(RUSAGE_THREAD, &reactor->rusage);
-	spdk_poller_register(&reactor->rusage_poller, get_rusage, reactor, reactor->lcore, 1000000);
-#endif
+	if (g_context_switch_monitor_enabled) {
+		_spdk_reactor_context_switch_monitor_start(reactor, NULL);
+	}
 	while (1) {
 		bool took_action = false;
 
@@ -403,13 +450,11 @@ _spdk_reactor_run(void *arg)
 		}
 
 		if (g_reactor_state != SPDK_REACTOR_STATE_RUNNING) {
-#ifdef DEBUG
-			spdk_poller_unregister(&reactor->rusage_poller, NULL);
-#endif
 			break;
 		}
 	}
 
+	_spdk_reactor_context_switch_monitor_stop(reactor, NULL);
 	spdk_free_thread();
 	return 0;
 }

lib/event/rpc/app_rpc.c

@@ -33,6 +33,7 @@
 
 #include "spdk/stdinc.h"
 
+#include "spdk/event.h"
 #include "spdk/rpc.h"
 #include "spdk/util.h"
 
@@ -108,3 +109,47 @@ invalid:
 	free_rpc_kill_instance(&req);
 }
 SPDK_RPC_REGISTER("kill_instance", spdk_rpc_kill_instance)
+
+
+struct rpc_context_switch_monitor {
+	bool enabled;
+};
+
+static const struct spdk_json_object_decoder rpc_context_switch_monitor_decoders[] = {
+	{"enabled", offsetof(struct rpc_context_switch_monitor, enabled), spdk_json_decode_bool},
+};
+
+static void
+spdk_rpc_context_switch_monitor(struct spdk_jsonrpc_request *request,
+				const struct spdk_json_val *params)
+{
+	struct rpc_context_switch_monitor req = {};
+	struct spdk_json_write_ctx *w;
+
+	if (params != NULL) {
+		if (spdk_json_decode_object(params, rpc_context_switch_monitor_decoders,
+					    SPDK_COUNTOF(rpc_context_switch_monitor_decoders),
+					    &req)) {
+			SPDK_DEBUGLOG(SPDK_TRACE_REACTOR, "spdk_json_decode_object failed\n");
+			spdk_jsonrpc_send_error_response(request, SPDK_JSONRPC_ERROR_INVALID_PARAMS, "Invalid parameters");
+			return;
+		}
+
+		spdk_reactor_enable_context_switch_monitor(req.enabled);
+	}
+
+	w = spdk_jsonrpc_begin_result(request);
+	if (w == NULL) {
+		return;
+	}
+
+	spdk_json_write_object_begin(w);
+
+	spdk_json_write_name(w, "enabled");
+	spdk_json_write_bool(w, spdk_reactor_context_switch_monitor_enabled());
+
+	spdk_json_write_object_end(w);
+	spdk_jsonrpc_end_result(request, w);
+}
+
+SPDK_RPC_REGISTER("context_switch_monitor", spdk_rpc_context_switch_monitor)

scripts/rpc.py

@@ -564,5 +564,18 @@ def get_rpc_methods(args):
 p = subparsers.add_parser('get_rpc_methods', help='Get list of supported RPC methods')
 p.set_defaults(func=get_rpc_methods)
 
+def context_switch_monitor(args):
+    params = {}
+    if args.enable:
+        params['enabled'] = True
+    if args.disable:
+        params['enabled'] = False
+    print_dict(jsonrpc_call('context_switch_monitor', params))
+
+p = subparsers.add_parser('context_switch_monitor', help='Control whether the context switch monitor is enabled')
+p.add_argument('-e', '--enable', action='store_true', help='Enable context switch monitoring')
+p.add_argument('-d', '--disable', action='store_true', help='Disable context switch monitoring')
+p.set_defaults(func=context_switch_monitor)
+
 args = parser.parse_args()
 args.func(args)