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input = saug->forward({input}).front();
}
auto output = fl::pkg::runtime::forwardSequentialModuleWithPadMask(
input, ntwrk, batch[kDurationIdx]);
fl::sync();
meters.critfwdtimer.resume();
auto loss =
crit->forward({output, fl::noGrad(batch[kTargetIdx])}).front();
fl::sync();
meters.fwdtimer.stopAndIncUnit();
meters.critfwdtimer.stopAndIncUnit();
if (FLAGS_fl_amp_use_mixed_precision) {
++scaleCounter;
loss = loss * scaleFactor;
}
if (af::anyTrue<bool>(af::isNaN(loss.array())) ||
af::anyTrue<bool>(af::isInf(loss.array()))) {
if (FLAGS_fl_amp_use_mixed_precision &&
scaleFactor >= fl::kAmpMinimumScaleFactorValue) {
scaleFactor = scaleFactor / 2.0f;
FL_VLOG(2) << "AMP: Scale factor decreased. New value:\t"
<< scaleFactor;
scaleCounter = 1;
retrySample = true;
continue;
} else {
LOG(FATAL) << "Loss has NaN values. Samples - "
<< join(",", readSampleIds(batch[kSampleIdx]));
}
}
if (hasher(join(",", readSampleIds(batch[kSampleIdx]))) % 100 <=
FLAGS_pcttraineval) {
evalOutput(output.array(), batch[kTargetIdx], meters.train);
}
// backward
meters.bwdtimer.resume();
netopt->zeroGrad();
loss.backward();
if (reducer) {
reducer->finalize();
}
fl::sync();
meters.bwdtimer.stopAndIncUnit();
// optimizer
meters.optimtimer.resume();
// scale down gradients by batchsize
for (const auto& p : ntwrk->params()) {
if (!p.isGradAvailable()) {
continue;
}
p.grad() = p.grad() / (FLAGS_batchsize * scaleFactor);
if (FLAGS_fl_amp_use_mixed_precision) {
if (af::anyTrue<bool>(af::isNaN(p.grad().array())) ||
af::anyTrue<bool>(af::isInf(p.grad().array()))) {
if (scaleFactor >= fl::kAmpMinimumScaleFactorValue) {
scaleFactor = scaleFactor / 2.0f;
FL_VLOG(2) << "AMP: Scale factor decreased. New value:\t"
<< scaleFactor;
retrySample = true;
}
scaleCounter = 1;
break;
}
}
}
if (retrySample) {
meters.optimtimer.stop();
continue;
}
meters.train.loss.add((loss / scaleFactor).array());
} while (retrySample);
// clamp gradients
if (FLAGS_maxgradnorm > 0) {
auto params = ntwrk->params();
fl::clipGradNorm(params, FLAGS_maxgradnorm);
}
// update weights
netopt->step();
fl::sync();
meters.optimtimer.stopAndIncUnit();
// update scale factor
if (FLAGS_fl_amp_use_mixed_precision && scaleFactor < kMaxScaleFactor) {
if (scaleCounter % kScaleFactorUpdateInterval == 0) {
scaleFactor *= 2;
FL_VLOG(2) << "AMP: Scale factor doubled. New value:\t"
<< scaleFactor;
} else {
scaleFactor += 2;