Report log likelihood for label smoothing

fairseq/criterions/label_smoothed_cross_entropy.py

@@ -65,9 +65,11 @@ class LabelSmoothedCrossEntropyCriterion(FairseqCriterion):
         lprobs = model.get_normalized_probs(net_output, log_probs=True)
         target = sample['target'].view(-1)
         loss = LabelSmoothedNLLLoss.apply(lprobs, target, self.eps, self.padding_idx, self.weights, reduce)
+        nll_loss = F.nll_loss(lprobs, target, size_average=False, ignore_index=self.padding_idx, reduce=reduce)
         sample_size = sample['target'].size(0) if self.args.sentence_avg else sample['ntokens']
         logging_output = {
             'loss': loss.data[0] if reduce else loss.data,
+            'nll_loss': nll_loss.data[0] if reduce else loss.data,
             'sample_size': sample_size,
         }
         return loss, sample_size, logging_output
@@ -78,4 +80,5 @@ class LabelSmoothedCrossEntropyCriterion(FairseqCriterion):
         sample_size = sum(log.get('sample_size', 0) for log in logging_outputs)
         return {
             'loss': sum(log.get('loss', 0) for log in logging_outputs) / sample_size / math.log(2),
+            'nll_loss': sum(log.get('nll_loss', 0) for log in logging_outputs) / sample_size / math.log(2),
         }

train.py

@@ -150,6 +150,7 @@ def train(args, epoch, batch_offset, trainer, dataset, max_positions):
         sample_without_replacement=args.sample_without_replacement,
         sort_by_source_size=(epoch <= args.curriculum))
     loss_meter = AverageMeter()
+    nll_loss_meter = AverageMeter()
     bsz_meter = AverageMeter()    # sentences per batch
     wpb_meter = AverageMeter()    # words per batch
     wps_meter = TimeMeter()       # words per second
@@ -164,6 +165,11 @@ def train(args, epoch, batch_offset, trainer, dataset, max_positions):
             del loss_dict['loss']  # don't include in extra_meters or extra_postfix
 
             ntokens = sum(s['ntokens'] for s in sample)
+
+            if 'nll_loss' in loss_dict:
+                nll_loss = loss_dict['nll_loss']
+                nll_loss_meter.update(nll_loss, ntokens)
+
             nsentences = sum(s['net_input']['src_tokens'].size(0) for s in sample)
             loss_meter.update(loss, nsentences if args.sentence_avg else ntokens)
             bsz_meter.update(nsentences)
@@ -193,7 +199,9 @@ def train(args, epoch, batch_offset, trainer, dataset, max_positions):
 
         t.print(collections.OrderedDict([
             ('train loss', round(loss_meter.avg, 2)),
-            ('train ppl', get_perplexity(loss_meter.avg)),
+            ('train ppl', get_perplexity(nll_loss_meter.avg
+                                         if nll_loss_meter.count > 0
+                                         else loss_meter.avg)),
             ('s/checkpoint', round(wps_meter.elapsed_time)),
             ('words/s', round(wps_meter.avg)),
             ('words/batch', round(wpb_meter.avg)),
@@ -242,16 +250,21 @@ def validate(args, epoch, trainer, dataset, max_positions, subset):
         descending=True,  # largest batch first to warm the caching allocator
     )
     loss_meter = AverageMeter()
+    nll_loss_meter = AverageMeter()
     extra_meters = collections.defaultdict(lambda: AverageMeter())
 
     prefix = 'valid on \'{}\' subset'.format(subset)
     with utils.build_progress_bar(args, itr, epoch, prefix) as t:
         for _, sample in data.skip_group_enumerator(t, args.num_gpus):
             loss_dict = trainer.valid_step(sample)
+            ntokens = sum(s['ntokens'] for s in sample)
             loss = loss_dict['loss']
             del loss_dict['loss']  # don't include in extra_meters or extra_postfix
 
-            ntokens = sum(s['ntokens'] for s in sample)
+            if 'nll_loss' in loss_dict:
+                nll_loss = loss_dict['nll_loss']
+                nll_loss_meter.update(nll_loss, ntokens)
+
             loss_meter.update(loss, ntokens)
 
             extra_postfix = []
@@ -265,7 +278,9 @@ def validate(args, epoch, trainer, dataset, max_positions, subset):
 
         t.print(collections.OrderedDict([
             ('valid loss', round(loss_meter.avg, 2)),
-            ('valid ppl', get_perplexity(loss_meter.avg)),
+            ('valid ppl', get_perplexity(nll_loss_meter.avg
+                                         if nll_loss_meter.count > 0
+                                         else loss_meter.avg)),
         ] + [
             (k, meter.avg)
             for k, meter in extra_meters.items()