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Avoid generating pseudo random numbers that are multiple of 5: this helps

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spread the load over multiple cpus without havind to rely on work stealing.
This commit is contained in:
Benoit Steiner 2016-06-14 17:51:47 -07:00
parent 4c61f00838
commit aedc5be1d6
1 changed files with 11 additions and 8 deletions
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19
unsupported/Eigen/CXX11/src/ThreadPool/NonBlockingThreadPool.h
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@ -99,10 +99,12 @@ class NonBlockingThreadPoolTempl : public Eigen::ThreadPoolInterface {
typedef typename Environment::EnvThread Thread; typedef typename Environment::EnvThread Thread;
struct PerThread { struct PerThread {
bool inited; PerThread() : pool(NULL), index(-1) {
rand = std::hash<std::thread::id>()(std::this_thread::get_id());
}
NonBlockingThreadPoolTempl* pool; // Parent pool, or null for normal threads. NonBlockingThreadPoolTempl* pool; // Parent pool, or null for normal threads.
unsigned index; // Worker thread index in pool. unsigned index; // Worker thread index in pool.
unsigned rand; // Random generator state. uint64_t rand; // Random generator state.
}; };
Environment env_; Environment env_;
@ -235,17 +237,18 @@ class NonBlockingThreadPoolTempl : public Eigen::ThreadPoolInterface {
return -1; return -1;
} }
PerThread* GetPerThread() { static EIGEN_STRONG_INLINE PerThread* GetPerThread() {
EIGEN_THREAD_LOCAL PerThread per_thread_; EIGEN_THREAD_LOCAL PerThread per_thread_;
PerThread* pt = &per_thread_; PerThread* pt = &per_thread_;
if (pt->inited) return pt;
pt->inited = true;
pt->rand = static_cast<unsigned>(std::hash<std::thread::id>()(std::this_thread::get_id()));
return pt; return pt;
} }
static unsigned Rand(unsigned* state) { static EIGEN_STRONG_INLINE unsigned Rand(uint64_t* state) {
return *state = *state * 1103515245 + 12345; uint64_t current = *state;
// Update the internal state
*state = current * 6364136223846793005ULL + 0xda3e39cb94b95bdbULL;
// Generate the random output (using the PCG-XSH-RS scheme)
return (current ^ (current >> 22)) >> (22 + (current >> 61));
} }
}; };