linux-gen: sched: add spread weight config file option

Add new config file option to control scheduler internal queue
preference ratio.

Signed-off-by: Petri Savolainen <petri.savolainen@linaro.org>
Reviewed-by: Bill Fischofer <bill.fischofer@linaro.org>
Signed-off-by: Maxim Uvarov <maxim.uvarov@linaro.org>

3 files changed, 45 insertions, 12 deletions

diff --git a/config/odp-linux-generic.conf b/config/odp-linux-generic.conf
index af651d7f6..2417d23f2 100644
--- a/config/odp-linux-generic.conf
+++ b/config/odp-linux-generic.conf
@@ -16,7 +16,7 @@
 
 # Mandatory fields
 odp_implementation = "linux-generic"
-config_file_version = "0.1.1"
+config_file_version = "0.1.2"
 
 # Shared memory options
 shm: {
@@ -80,13 +80,27 @@ queue_basic: {
 }
 
 sched_basic: {
-	# Priority level spread. Each priority level is spread into multiple
-	# scheduler internal queues. A higher spread value typically improves
-	# parallelism and thus is better for high thread counts, but causes
-	# uneven service level for low thread counts. Typically, optimal
-	# value is the number of threads using the scheduler.
+	# Priority level spread
+	#
+	# Each priority level is spread into multiple scheduler internal queues.
+	# This value defines the number of those queues. Minimum value is 1.
+	# Each thread prefers one of the queues over other queues. A higher
+	# spread value typically improves parallelism and thus is better for
+	# high thread counts, but causes uneven service level for low thread
+	# counts. Typically, optimal value is the number of threads using
+	# the scheduler.
 	prio_spread = 4
 
+	# Weight of the preferred scheduler internal queue
+	#
+	# Each thread prefers one of the internal queues over other queues.
+	# This value controls how many times the preferred queue is polled
+	# between a poll to another internal queue. Minimum value is 1. A higher
+	# value typically improves parallelism as threads work mostly on their
+	# preferred queues, but causes uneven service level for low thread
+	# counts as non-preferred queues are served less often
+	prio_spread_weight = 63
+
 	# Burst size configuration per priority. The first array element
 	# represents the highest queue priority. The scheduler tries to get
 	# burst_size_default[prio] events from a queue and stashes those that
diff --git a/platform/linux-generic/odp_schedule_basic.c b/platform/linux-generic/odp_schedule_basic.c
index 58396293b..214d42c8b 100644
--- a/platform/linux-generic/odp_schedule_basic.c
+++ b/platform/linux-generic/odp_schedule_basic.c
@@ -58,10 +58,12 @@ ODP_STATIC_ASSERT((ODP_SCHED_PRIO_NORMAL > 0) &&
 
 /* A thread polls a non preferred sched queue every this many polls
  * of the prefer queue. */
-#define PREFER_RATIO 64
+#define MAX_PREFER_WEIGHT 63
+#define MIN_PREFER_WEIGHT 1
+#define MAX_PREFER_RATIO  (MAX_PREFER_WEIGHT + 1)
 
 /* Spread weight table */
-#define SPREAD_TBL_SIZE ((MAX_SPREAD - 1) * PREFER_RATIO)
+#define SPREAD_TBL_SIZE ((MAX_SPREAD - 1) * MAX_PREFER_RATIO)
 
 /* Maximum number of packet IO interfaces */
 #define NUM_PKTIO ODP_CONFIG_PKTIO_ENTRIES
@@ -182,6 +184,7 @@ typedef struct {
 		uint8_t burst_default[NUM_PRIO];
 		uint8_t burst_max[NUM_PRIO];
 		uint8_t num_spread;
+		uint8_t prefer_ratio;
 	} config;
 
 	uint16_t         max_spread;
@@ -256,13 +259,29 @@ static int read_config_file(sched_global_t *sched)
 	}
 
 	if (val > MAX_SPREAD || val < MIN_SPREAD) {
-		ODP_ERR("Bad value %s = %u\n", str, val);
+		ODP_ERR("Bad value %s = %u [min: %u, max: %u]\n", str, val,
+			MIN_SPREAD, MAX_SPREAD);
 		return -1;
 	}
 
 	sched->config.num_spread = val;
 	ODP_PRINT("  %s: %i\n", str, val);
 
+	str = "sched_basic.prio_spread_weight";
+	if (!_odp_libconfig_lookup_int(str, &val)) {
+		ODP_ERR("Config option '%s' not found.\n", str);
+		return -1;
+	}
+
+	if (val > MAX_PREFER_WEIGHT || val < MIN_PREFER_WEIGHT) {
+		ODP_ERR("Bad value %s = %u [min: %u, max: %u]\n", str, val,
+			MIN_PREFER_WEIGHT, MAX_PREFER_WEIGHT);
+		return -1;
+	}
+
+	sched->config.prefer_ratio = val + 1;
+	ODP_PRINT("  %s: %i\n", str, val);
+
 	str = "sched_basic.burst_size_default";
 	if (_odp_libconfig_lookup_array(str, burst_val, NUM_PRIO) !=
 	    NUM_PRIO) {
@@ -329,7 +348,7 @@ static void sched_local_init(void)
 	for (i = 0; i < SPREAD_TBL_SIZE; i++) {
 		sched_local.spread_tbl[i] = spread;
 
-		if (num_spread > 1 && (i % PREFER_RATIO) == 0) {
+		if (num_spread > 1 && (i % MAX_PREFER_RATIO) == 0) {
 			sched_local.spread_tbl[i] = prio_spread_index(spread +
 								      offset);
 			offset++;
@@ -364,7 +383,7 @@ static int schedule_init_global(void)
 	}
 
 	/* When num_spread == 1, only spread_tbl[0] is used. */
-	sched->max_spread = (sched->config.num_spread - 1) * PREFER_RATIO;
+	sched->max_spread = (sched->config.num_spread - 1) * MAX_PREFER_RATIO;
 	sched->shm  = shm;
 	odp_spinlock_init(&sched->mask_lock);
 
diff --git a/platform/linux-generic/test/process-mode.conf b/platform/linux-generic/test/process-mode.conf
index d80df25c4..7a06544ab 100644
--- a/platform/linux-generic/test/process-mode.conf
+++ b/platform/linux-generic/test/process-mode.conf
@@ -1,6 +1,6 @@
 # Mandatory fields
 odp_implementation = "linux-generic"
-config_file_version = "0.1.1"
+config_file_version = "0.1.2"
 
 # Shared memory options
 shm: {