summary |
shortlog |
log |
commit | commitdiff |
tree
raw |
patch |
inline | side by side (from parent 1:
3811206)
Calling lock.test_and_set() in a tight loop creates expensive
memory synchronizations among processors and penalize other
running threads. So syncronize only only once at the beginning
with fetch_sub() and then loop on a simple load() that puts much
less pressure on the system.
Reported about 2-3% speed up on various systems.
Patch by Ronald de Man.
No functional change.
const size_t MAX_SPLITPOINTS_PER_THREAD = 8;
const size_t MAX_SLAVES_PER_SPLITPOINT = 4;
const size_t MAX_SPLITPOINTS_PER_THREAD = 8;
const size_t MAX_SLAVES_PER_SPLITPOINT = 4;
-/// Spinlock class wraps low level atomic operations to provide spin lock functionality
+
+/// Spinlock class wraps low level atomic operations to provide a spin lock
- Spinlock() { std::atomic_flag_clear(&lock); }
- void acquire() { while (lock.test_and_set(std::memory_order_acquire)) {} }
- void release() { lock.clear(std::memory_order_release); }
+ Spinlock() { lock = 1; } // Init here to workaround a bug with MSVC 2013
+ void acquire() {
+ while (lock.fetch_sub(1, std::memory_order_acquire) != 1)
+ while (lock.load(std::memory_order_relaxed) <= 0) {}
+ }
+ void release() { lock.store(1, std::memory_order_release); }