From 09ad928f2024d986fbae896c645f56ff3953f152 Mon Sep 17 00:00:00 2001
From: Martin Karsten <mkarsten@uwaterloo.ca>
Date: Fri, 29 Jun 2018 15:16:13 -0400
Subject: [PATCH] - rename BargingMutex to SpinMutex and add proper barging
mutex without atomic spinning
---
src/runtime/BlockingSync.h | 45 ++++++++++++++++++++++++++++++++++----
src/testoptions.h | 1 +
2 files changed, 42 insertions(+), 4 deletions(-)
diff --git a/src/runtime/BlockingSync.h b/src/runtime/BlockingSync.h
index 8af41f0..1ba9d62 100644
--- a/src/runtime/BlockingSync.h
+++ b/src/runtime/BlockingSync.h
@@ -410,8 +410,43 @@ public:
}
};
-template<typename Semaphore, bool OwnerLock, size_t SpinStart, size_t SpinEnd>
+template<typename Lock, bool OwnerLock = false, typename BQ = BlockingQueue<Lock>>
class BargingMutex {
+ Lock lock;
+ StackContext* owner;
+ BQ bq;
+
+protected:
+ bool internalAcquire(bool wait, const Time& timeout = Time::zero()) {
+ StackContext* cs = CurrStack();
+ for (;;) {
+ lock.acquire();
+ if (!owner) break;
+ if (owner == cs) { GENASSERT1(OwnerLock, FmtHex(owner)); break; }
+ if (!bq.block(lock, wait, timeout)) return false;
+ }
+ owner = cs;
+ lock.release();
+ return true;
+ }
+
+public:
+ BargingMutex() : owner(nullptr) {}
+ bool test() { return owner != nullptr; }
+
+ bool tryAcquire() { return internalAcquire(false); }
+ bool acquire(const Time& timeout = Time::zero()) { return internalAcquire(true, timeout); }
+
+ void release() {
+ ScopedLock<Lock> al(lock);
+ GENASSERT1(owner == CurrStack(), FmtHex(owner));
+ owner = nullptr;
+ bq.unblock();
+ }
+};
+
+template<typename Semaphore, bool OwnerLock, size_t SpinStart, size_t SpinEnd>
+class SpinMutex {
StackContext* owner;
Semaphore sem;
@@ -442,7 +477,7 @@ protected:
}
public:
- BargingMutex() : owner(nullptr), sem(1) {}
+ SpinMutex() : owner(nullptr), sem(1) {}
bool test() { return __atomic_load_n(&owner, __ATOMIC_RELAXED) != nullptr; }
bool tryAcquire() { return internalAcquire(false); }
@@ -480,10 +515,12 @@ public:
template<typename Lock>
#if TESTING_MUTEX_FIFO
class Mutex : public FifoMutex<Lock> {};
+#elif TESTING_MUTEX_BARGING
+class Mutex : public BargingMutex<Lock> {};
#elif TESTING_MUTEX_SPIN
-class Mutex : public BargingMutex<Benaphore<BargingSemaphore<Lock>>, false, 4, 1024> {};
+class Mutex : public SpinMutex<Benaphore<BargingSemaphore<Lock>>, false, 4, 1024> {};
#else
-class Mutex : public BargingMutex<Benaphore<BargingSemaphore<Lock>>, false, 1, 0> {};
+class Mutex : public SpinMutex<Benaphore<BargingSemaphore<Lock>>, false, 1, 0> {};
#endif
// simple blocking RW lock: release alternates; new readers block when writer waits -> no starvation
diff --git a/src/testoptions.h b/src/testoptions.h
index 93009a7..eaa907b 100644
--- a/src/testoptions.h
+++ b/src/testoptions.h
@@ -20,6 +20,7 @@
//#define TESTING_BLOCKING_CONCURRENT 1 // using MPSC blocking semantics (no prio levels)
//#define TESTING_IDLE_SPIN 128 // spin before idle/halt threshold
//#define TESTING_MUTEX_FIFO 1 // use fifo/baton mutex
+//#define TESTING_MUTEX_BARGING 1 // use blocking/barging mutex
//#define TESTING_MUTEX_SPIN 1 // spin before block in non-fifo mutex
//#define TESTING_PLACEMENT_RR 1 // RR placement, instead of load-based staging
#define TESTING_WAKE_CLUSTER 1 // try waking idle processor on cluster backlog
--
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