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Merge pull request #158 from walisser/upstream

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improved OpenMP SpecCache::Populate
This commit is contained in:
Paul Licameli 2016-08-31 17:36:40 -04:00 committed by GitHub
commit d16c722d90
1 changed files with 34 additions and 44 deletions
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78
src/WaveClip.cpp
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@ -43,7 +43,6 @@
#include "Experimental.h"
//#undef _OPENMP
#ifdef _OPENMP
#include <omp.h>
#else
@ -930,8 +929,18 @@ bool SpecCache::CalculateOneSpectrum
int correctedX = (floor(0.5 + xx + timeCorrection * pixelsPerSecond / rate));
if (correctedX >= lowerBoundX && correctedX < upperBoundX)
result = true,
out[half * correctedX + bin] += power;
{
result = true;
int index = half * correctedX + bin;
#ifdef _OPENMP
// This assignment can race if index reaches into another thread's bins.
// The probability of a race very low, so this carries little overhead,
// about 5% slower vs allowing it to race.
#pragma omp atomic update
#endif
out[index] += power;
}
}
}
}
@ -990,29 +999,6 @@ void SpecCache::Populate
if (!autocorrelation)
ComputeSpectrogramGainFactors(fftLen, rate, frequencyGain, gainFactors);
#ifdef _OPENMP
// todo: query # of threads or make it a setting
const int numThreads = 8;
omp_set_num_threads(numThreads);
// We need certain per-thread data for thread safety
// Assumes WaveTrackCache is reentrant since it takes a const* to WaveTrack
struct {
WaveTrackCache* cache;
float* scratch;
} threadLocalStorage[numThreads];
// May as well use existing data for one of the threads
assert(numThreads > 0);
threadLocalStorage[0].cache = &waveTrackCache;
threadLocalStorage[0].scratch = &scratch[0];
for (int i = 1; i < numThreads; i++) {
threadLocalStorage[i].cache = new WaveTrackCache( waveTrackCache.GetTrack() );
threadLocalStorage[i].scratch = new float[scratchSize];
}
#endif
// Loop over the ranges before and after the copied portion and compute anew.
// One of the ranges may be empty.
for (int jj = 0; jj < 2; ++jj) {
@ -1020,24 +1006,36 @@ void SpecCache::Populate
const int upperBoundX = jj == 0 ? copyBegin : numPixels;
#ifdef _OPENMP
#pragma omp parallel for
// Storage for mutable per-thread data.
// private clause ensures one copy per thread
struct ThreadLocalStorage {
ThreadLocalStorage() { cache = nullptr; }
~ThreadLocalStorage() { delete cache; }
void init(WaveTrackCache &waveTrackCache, size_t scratchSize) {
if (!cache) {
cache = new WaveTrackCache(waveTrackCache.GetTrack());
scratch.resize(scratchSize);
}
}
WaveTrackCache* cache;
std::vector<float> scratch;
} tls;
#pragma omp parallel for private(tls)
#endif
for (auto xx = lowerBoundX; xx < upperBoundX; ++xx)
{
#ifdef _OPENMP
int threadNum = omp_get_thread_num();
assert(threadNum >=0 && threadNum < numThreads);
WaveTrackCache* cache = threadLocalStorage[threadNum].cache;
float* buffer = threadLocalStorage[threadNum].scratch;
tls.init(waveTrackCache, scratchSize);
WaveTrackCache& cache = *tls.cache;
float* buffer = &tls.scratch[0];
#else
WaveTrackCache* cache = &waveTrackCache;
WaveTrackCache& cache = waveTrackCache;
float* buffer = &scratch[0];
#endif
CalculateOneSpectrum(
settings, *cache, xx, numSamples,
settings, cache, xx, numSamples,
offset, rate, pixelsPerSecond,
lowerBoundX, upperBoundX,
gainFactors, buffer, &freq[0]);
@ -1098,14 +1096,6 @@ void SpecCache::Populate
}
}
}
#ifdef _OPENMP
for (int i = 1; i < numThreads; i++)
{
delete[] threadLocalStorage[i].scratch;
delete threadLocalStorage[i].cache;
}
#endif
}
bool WaveClip::GetSpectrogram(WaveTrackCache &waveTrackCache,