diff --git a/egs/librispeech/ASR/pruned_transducer_stateless7/train.py b/egs/librispeech/ASR/pruned_transducer_stateless7/train.py
index 88b78e92c..f5d3cd3a6 100755
--- a/egs/librispeech/ASR/pruned_transducer_stateless7/train.py
+++ b/egs/librispeech/ASR/pruned_transducer_stateless7/train.py
@@ -851,7 +851,8 @@ def train_one_epoch(
                 f"Epoch {params.cur_epoch}, "
                 f"batch {batch_idx}, loss[{loss_info}], "
                 f"tot_loss[{tot_loss}], batch size: {batch_size}, "
-                f"lr: {cur_lr:.2e}"
+                f"lr: {cur_lr:.2e}, " +
+                (f"grad_scale: {scaler.scale}" if params.use_fp16 else "")
             )
 
             if tb_writer is not None:
@@ -865,6 +866,12 @@ def train_one_epoch(
                 tot_loss.write_summary(
                     tb_writer, "train/tot_", params.batch_idx_train
                 )
+                if params.use_fp16:
+                    tb_writer.add_scalar(
+                        "train/grad_scale", scaler.scale, params.batch_idx_train
+                    )
+
+
 
         if batch_idx % params.valid_interval == 0 and not params.print_diagnostics:
             logging.info("Computing validation loss")
diff --git a/icefall/diagnostics.py b/icefall/diagnostics.py
index c26e37de4..ce35d2bdf 100644
--- a/icefall/diagnostics.py
+++ b/icefall/diagnostics.py
@@ -82,11 +82,18 @@ def get_tensor_stats(
     elif stats_type == "positive":
         x = (x > 0).to(dtype=torch.float)
     else:
-        assert stats_type == "value"
+        assert stats_type in [ "value", "max", "min" ]
 
     sum_dims = [d for d in range(x.ndim) if d != dim]
     if len(sum_dims) > 0:
-        x = torch.sum(x, dim=sum_dims)
+        if stats_type == "max":
+            for dim in reversed(sum_dims):
+                x = torch.max(x, dim=dim)[0]
+        elif stats_type == "min":
+            for dim in reversed(sum_dims):
+                x = torch.min(x, dim=dim)[0]
+        else:
+            x = torch.sum(x, dim=sum_dims)
     x = x.flatten()
     return x, count
 
@@ -117,7 +124,7 @@ class TensorDiagnostic(object):
         self.stats = None  # we'll later assign a list to this data member.  It's a list of dict.
 
         # the keys into self.stats[dim] are strings, whose values can be
-        # "abs", "value", "positive", "rms", "value".
+        # "abs", "max", "min" ,"value", "positive", "rms", "value".
         # The values e.g. self.stats[dim]["rms"] are lists of dataclass TensorAndCount,
         # containing a tensor and its associated count (which is the sum of the other dims
         # that we aggregated over, e.g. the number of frames and/or batch elements and/or
@@ -149,11 +156,11 @@ class TensorDiagnostic(object):
         for dim in range(ndim):
             this_dim_stats = self.stats[dim]
             if ndim > 1:
-                stats_types = ["abs", "positive", "value", "rms"]
+                stats_types = ["abs", "max", "min", "positive", "value", "rms"]
                 if x.shape[dim] <= self.opts.max_eig_dim:
                     stats_types.append("eigs")
             else:
-                stats_types = ["value", "abs"]
+                stats_types = ["value", "abs", "max", "min"]
 
             for stats_type in stats_types:
                 stats, count = get_tensor_stats(x, dim, stats_type)
@@ -168,7 +175,12 @@ class TensorDiagnostic(object):
                     continue
                 for s in this_dim_stats[stats_type]:
                     if s.tensor.shape == stats.shape:
-                        s.tensor += stats
+                        if stats_type == "max":
+                            s.tensor = torch.maximum(s.tensor, stats)
+                        elif stats_type == "min":
+                            s.tensor = torch.minimum(s.tensor, stats)
+                        else:
+                            s.tensor += stats
                         s.count += count
                         done = True
                         break
@@ -199,13 +211,17 @@ class TensorDiagnostic(object):
                     assert stats_type == "eigs"
                     continue
 
+
+                def get_count(count):
+                    return 1 if stats_type in ["max", "min"] else count
+
                 if len(stats_list) == 1:
-                    stats = stats_list[0].tensor / stats_list[0].count
+                    stats = stats_list[0].tensor / get_count(stats_list[0].count)
                 else:
                     # a dimension that has variable size in different nnet
                     # forwards, e.g. a time dimension in an ASR model.
                     stats = torch.cat(
-                        [x.tensor / x.count for x in stats_list], dim=0
+                        [x.tensor / get_count(x.count) for x in stats_list], dim=0
                     )
 
                 if stats_type == "eigs":