chore: Configurable quantum

runtime/include/runtime.h

@@ -91,3 +91,4 @@ print_runtime_scheduler(enum RUNTIME_SCHEDULER variant)
 
 extern enum RUNTIME_SCHEDULER runtime_scheduler;
 extern bool                   runtime_preemption_enabled;
+extern uint32_t               runtime_quantum_us;

runtime/include/software_interrupt.h

@@ -11,9 +11,6 @@
 
 #include "debuglog.h"
 
-#define SOFTWARE_INTERRUPT_TIME_TO_START_IN_USEC     (2 * 1000) /* 2 ms */
-#define SOFTWARE_INTERRUPT_INTERVAL_DURATION_IN_USEC (1 * 1000) /* 1 ms */
-
 /************
  * Externs  *
  ***********/

runtime/src/main.c

@@ -41,7 +41,8 @@ enum RUNTIME_SCHEDULER runtime_scheduler = RUNTIME_SCHEDULER_FIFO;
 int                    runtime_worker_core_count;
 
 
-bool runtime_preemption_enabled = true;
+bool     runtime_preemption_enabled = true;
+uint32_t runtime_quantum_us         = 5000; /* 5ms */
 
 /**
  * Returns instructions on use of CLI if used incorrectly
@@ -221,6 +222,17 @@ runtime_configure()
 	if (preempt_disable != NULL && strcmp(preempt_disable, "false") != 0) runtime_preemption_enabled = false;
 	printf("\tPreemption: %s\n", runtime_preemption_enabled ? "Enabled" : "Disabled");
 
+	/* Runtime Quantum */
+	char *quantum_raw = getenv("SLEDGE_QUANTUM_US");
+	if (quantum_raw != NULL) {
+		long quantum = atoi(quantum_raw);
+		if (unlikely(quantum <= 0)) panic("SLEDGE_QUANTUM_US must be a positive integer, saw %ld\n", quantum);
+		if (unlikely(quantum > 999999))
+			panic("SLEDGE_QUANTUM_US must be less than 999999 ms, saw %ld\n", quantum);
+		runtime_quantum_us = (uint32_t)quantum;
+	}
+	printf("\tQuantum: %u us\n", runtime_quantum_us);
+
 	/* Runtime Perf Log */
 	char *runtime_sandbox_perf_log_path = getenv("SLEDGE_SANDBOX_PERF_LOG");
 	if (runtime_sandbox_perf_log_path != NULL) {
@@ -360,8 +372,7 @@ main(int argc, char **argv)
 	runtime_processor_speed_MHz = runtime_get_processor_speed_MHz();
 	if (unlikely(runtime_processor_speed_MHz == 0)) panic("Failed to detect processor speed\n");
 
-	software_interrupt_interval_duration_in_cycles = (uint64_t)SOFTWARE_INTERRUPT_INTERVAL_DURATION_IN_USEC
-	                                                 * runtime_processor_speed_MHz;
+	software_interrupt_interval_duration_in_cycles = (uint64_t)runtime_quantum_us * runtime_processor_speed_MHz;
 	printf("\tProcessor Speed: %u MHz\n", runtime_processor_speed_MHz);
 
 	runtime_set_resource_limits_to_max();

runtime/src/software_interrupt.c

@@ -197,7 +197,7 @@ software_interrupt_handle_signals(int signal_type, siginfo_t *signal_info, void
  *******************/
 
 /**
- * Arms the Interval Timer to start in 10ms and then trigger a SIGALRM every 5ms
+ * Arms the Interval Timer to start in one quantum and then trigger a SIGALRM every quantum
  */
 void
 software_interrupt_arm_timer(void)
@@ -207,8 +207,8 @@ software_interrupt_arm_timer(void)
 	struct itimerval interval_timer;
 
 	memset(&interval_timer, 0, sizeof(struct itimerval));
-	interval_timer.it_value.tv_usec    = SOFTWARE_INTERRUPT_TIME_TO_START_IN_USEC;
-	interval_timer.it_interval.tv_usec = SOFTWARE_INTERRUPT_INTERVAL_DURATION_IN_USEC;
+	interval_timer.it_value.tv_usec    = runtime_quantum_us;
+	interval_timer.it_interval.tv_usec = runtime_quantum_us;
 
 	int return_code = setitimer(ITIMER_REAL, &interval_timer, NULL);
 	if (return_code) {