scheduler: create and parse JSON values for dynamic scheduler params

Creates a JSON on scheduler side to return after .get_opts is called
and parses a JSON on .set_opts call.

The JSON passed to dynamic scheduler on .set_stats is a copy of a
pointer already available during RPC framework_set_scheduler call.

Getting and setting scheduler stats via RPC calls is going to be
implemented in the next patch in this series.

Change-Id: I62880a71066a140c74336a5725e7b10952008e5c
Signed-off-by: Krzysztof Karas <krzysztof.karas@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/11448
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Community-CI: Broadcom CI <spdk-ci.pdl@broadcom.com>
Community-CI: Mellanox Build Bot
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>

include/spdk/scheduler.h

@@ -224,6 +224,21 @@ struct spdk_scheduler {
 	 */
 	void (*balance)(struct spdk_scheduler_core_info *core_info, uint32_t count);
 
+	/**
+	 * Function to set scheduler parameters like load_limit.
+	 *
+	 * \param opts Pointer to spdk_json_val struct containing values of parameters
+	 * to be set in scheduler.
+	 */
+	int (*set_opts)(const struct spdk_json_val *opts);
+
+	/**
+	 * Function to get current scheduler parameters like load_limit.
+	 *
+	 * \param ctx Pointer to spdk_json_write_ctx struct to be filled with current parameters.
+	 */
+	void (*get_opts)(struct spdk_json_write_ctx *ctx);
+
 	TAILQ_ENTRY(spdk_scheduler)	link;
 };
 

lib/event/app_rpc.c

@@ -40,6 +40,7 @@
 #include "spdk/env.h"
 #include "spdk/scheduler.h"
 #include "spdk/thread.h"
+#include "spdk/json.h"
 
 #include "spdk/log.h"
 #include "spdk_internal/event.h"

lib/event/scheduler_static.c

@@ -56,10 +56,23 @@ balance_static(struct spdk_scheduler_core_info *cores, uint32_t core_count)
 {
 }
 
+static int
+set_opts_static(const struct spdk_json_val *opts)
+{
+	return 0;
+}
+
+static void
+get_opts_static(struct spdk_json_write_ctx *ctx)
+{
+}
+
 static struct spdk_scheduler scheduler = {
 	.name = "static",
 	.init = init_static,
 	.deinit = deinit_static,
 	.balance = balance_static,
+	.set_opts = set_opts_static,
+	.get_opts = get_opts_static,
 };
 SPDK_SCHEDULER_REGISTER(scheduler);

mk/spdk.lib_deps.mk

@@ -129,7 +129,7 @@ DEPDIRS-sock_posix := log sock util
 DEPDIRS-sock_uring := log sock util
 
 # module/scheduler
-DEPDIRS-scheduler_dynamic := event log thread util
+DEPDIRS-scheduler_dynamic := event log thread util json
 ifeq ($(SPDK_ROOT_DIR)/lib/env_dpdk,$(CONFIG_ENV))
 ifeq ($(OS),Linux)
 DEPDIRS-scheduler_dpdk_governor := event log

module/scheduler/dynamic/scheduler_dynamic.c

@@ -376,11 +376,60 @@ balance(struct spdk_scheduler_core_info *cores_info, uint32_t cores_count)
 	}
 }
 
+struct json_scheduler_opts {
+	uint8_t load_limit;
+	uint8_t core_limit;
+	uint8_t core_busy;
+};
+
+static const struct spdk_json_object_decoder sched_decoders[] = {
+	{"load_limit", offsetof(struct json_scheduler_opts, load_limit), spdk_json_decode_uint8, true},
+	{"core_limit", offsetof(struct json_scheduler_opts, core_limit), spdk_json_decode_uint8, true},
+	{"core_busy", offsetof(struct json_scheduler_opts, core_busy), spdk_json_decode_uint8, true},
+};
+
+static int
+set_opts(const struct spdk_json_val *opts)
+{
+	struct json_scheduler_opts scheduler_opts;
+
+	scheduler_opts.load_limit = g_scheduler_load_limit;
+	scheduler_opts.core_limit = g_scheduler_core_limit;
+	scheduler_opts.core_busy = g_scheduler_core_busy;
+
+	if (opts != NULL) {
+		if (spdk_json_decode_object_relaxed(opts, sched_decoders,
+						    SPDK_COUNTOF(sched_decoders), &scheduler_opts)) {
+			SPDK_ERRLOG("Decoding scheduler opts JSON failed\n");
+			return -1;
+		}
+	}
+
+	SPDK_NOTICELOG("Setting scheduler load limit to %d\n", scheduler_opts.load_limit);
+	g_scheduler_load_limit = scheduler_opts.load_limit;
+	SPDK_NOTICELOG("Setting scheduler core limit to %d\n", scheduler_opts.core_limit);
+	g_scheduler_core_limit = scheduler_opts.core_limit;
+	SPDK_NOTICELOG("Setting scheduler core busy to %d\n", scheduler_opts.core_busy);
+	g_scheduler_core_busy = scheduler_opts.core_busy;
+
+	return 0;
+}
+
+static void
+get_opts(struct spdk_json_write_ctx *ctx)
+{
+	spdk_json_write_named_uint8(ctx, "load_limit", g_scheduler_load_limit);
+	spdk_json_write_named_uint8(ctx, "core_limit", g_scheduler_core_limit);
+	spdk_json_write_named_uint8(ctx, "core_busy", g_scheduler_core_busy);
+}
+
 static struct spdk_scheduler scheduler_dynamic = {
 	.name = "dynamic",
 	.init = init,
 	.deinit = deinit,
 	.balance = balance,
+	.set_opts = set_opts,
+	.get_opts = get_opts,
 };
 
 SPDK_SCHEDULER_REGISTER(scheduler_dynamic);