Merge branch 'laws-simple-actor-test-timeout' into 'master'

[LAWS] Attempt to steal from all other workers instead of just one

Closes #6

See merge request i4/manycore/emper!66

emper/strategies/laws/LawsScheduler.cpp

@@ -94,24 +94,29 @@ auto LawsScheduler::nextFiber() -> Fiber* {
 		return fiber;
 	}
 
+	// TODO: The code below is nearly duplicated, besides the statsk
+	// part, in WsScheduler, deduplicate.
+	const workerid_t myWorkerId = Runtime::getWorkerId();
 	const workerid_t workerCount = runtime.getWorkerCount();
 	workerid_t startWorkerId = Runtime::rand() % workerCount;
+	// TODO: See how reducing the loop bound affects things.
+	for (workerid_t i = 0; i < workerCount; ++i) {
+		workerid_t victim = (startWorkerId + i) % workerCount;
 
-	if (unlikely(startWorkerId == Runtime::getWorkerId())) startWorkerId++;
-	workerid_t victim = startWorkerId % workerCount;
+		// Don't steal from ourselves.
+		if (unlikely(victim == myWorkerId)) continue;
 
-	poped = queues[victim]->popTop(&fiber);
-	if (poped) {
-		if constexpr (emper::STATS) {
-			auto flag = static_cast<unsigned int>(LawsStrategy::FiberSource::stolen);
-			fiber->setFlag(flag);
-		}
+		poped = queues[victim]->popTop(&fiber);
+		if (poped) {
+			if constexpr (emper::STATS) {
+				auto flag = static_cast<unsigned int>(LawsStrategy::FiberSource::stolen);
+				fiber->setFlag(flag);
+			}
 
-		return fiber;
+			return fiber;
+		}
 	}
 
-	// TODO: Reduce pressure on mainThreadQueue by only checking every N-th time.
-
 	// Try the "scheduled from anywhere" queue to get work as last resort.
 	fiber = dequeFiberFromAnywhereQueue();
 	if (fiber) {

emper/strategies/ws/WsScheduler.cpp

@@ -54,6 +54,8 @@ auto WsScheduler::nextFiber() -> Fiber* {
 		return fiber;
 	}
 
+	// TODO: The code below is nearly duplicated, besides the stats
+	// part, in LawsScheduler, deduplicate.
 	const workerid_t myWorkerId = Runtime::getWorkerId();
 	const workerid_t workerCount = runtime.getWorkerCount();
 	workerid_t startWorkerId = Runtime::rand() % workerCount;