fix(mge/quantization): fix histogram observer load and store issue

GitOrigin-RevId: b0a2b476e4490f960fc6fde48a715bbdab5ce128

python_module/megengine/quantization/__init__.py

@@ -6,7 +6,7 @@
 # software distributed under the License is distributed on an
 # "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 from .fake_quant import FakeQuantize
-from .observer import HistogramObserver, Observer
+from .observer import HistogramObserver, Observer, ObserverMode
 from .qconfig import (
     QConfig,
     calibration_qconfig,

python_module/megengine/quantization/observer.py

@@ -132,7 +132,7 @@ class MinMaxObserver(Observer):
                 (max_val - min_val) / (self.qmax - self.qmin), self.scale_limit,
             )
             # caculate zero_point
-            q_dict["zero_point"] = self.qmin - Round()((min_val / scale))
+            q_dict["zero_point"] = self.qmin - Round()((min_val / q_dict["scale"]))
 
         return q_dict
 
@@ -204,7 +204,7 @@ class HistogramObserver(MinMaxObserver):
         self.bins = bins
         self.upsample_rate = upsample_rate
         self.dst_nbins = _metadata_dict[dtype].qmax - _metadata_dict[dtype].qmin + 1
-        self.histogram = None
+        self.histogram = Buffer([0.0] * bins)
 
     def _non_linear_param_search(self):
         r"""Non-linear parameter search.
@@ -212,6 +212,12 @@ class HistogramObserver(MinMaxObserver):
         By selecting new min/max, we filter out outliers in input distribution.
         """
 
+        np_min_val = self.min_val.numpy()[0]
+        np_max_val = self.max_val.numpy()[0]
+        np_histogram = self.histogram.numpy()
+        assert len(np_histogram) == self.bins, "bins mistmatch"
+        bin_width = (np_max_val - np_min_val) / self.bins
+
         def _get_norm(delta_begin, delta_end, density, norm_type):
             r"""
             Compute the norm of the values uniformaly distributed between
@@ -233,9 +239,6 @@ class HistogramObserver(MinMaxObserver):
             Compute the quantization error if we use start_bin to end_bin as the
             min and max to do the quantization.
             """
-            np_min_val = self.min_val.numpy()[0]
-            np_max_val = self.max_val.numpy()[0]
-            bin_width = (np_max_val - np_min_val) / self.bins
 
             norm = 0.0
             dst_bin_width = (
@@ -262,7 +265,7 @@ class HistogramObserver(MinMaxObserver):
                     dst_bin_of_begin * dst_bin_width + dst_bin_width / 2
                 )
 
-                density = self.histogram[src_bin] / bin_width
+                density = np_histogram[src_bin] / bin_width
                 if dst_bin_of_begin == dst_bin_of_end:
                     # if src_bin is entirely within 1 dst_bin
                     delta_begin = src_bin_begin - dst_bin_of_begin_center
@@ -286,12 +289,9 @@ class HistogramObserver(MinMaxObserver):
                     norm = norm + _get_norm(delta_begin, delta_end, density, norm_type)
             return norm
 
-        assert len(self.histogram) == self.bins, "bins mistmatch"
-        bin_width = (self.max_val - self.min_val) / self.bins
-
         # cumulative sum
-        total = sum(self.histogram)
-        cSum = np.cumsum(self.histogram, axis=0)
+        total = sum(np_histogram)
+        cSum = np.cumsum(np_histogram, axis=0)
 
         stepsize = 1e-5  # granularity
         alpha = 0.0  # lower bound
@@ -400,46 +400,39 @@ class HistogramObserver(MinMaxObserver):
         x = x_orig.numpy()
         min_val = self.min_val.numpy()[0]
         max_val = self.max_val.numpy()[0]
+        histogram = self.histogram.numpy()
+        new_min = x.min()
+        new_max = x.max()
+
         if min_val == 0 or max_val == 0:
-            min_val = x.min()
-            max_val = x.max()
-            self.min_val.set_value(min_val)
-            self.max_val.set_value(max_val)
-            self.histogram, _ = np.histogram(x, self.bins, (min_val, max_val))
-            self.histogram = self.histogram.astype(np.float64)
+            new_histogram, _ = np.histogram(x, self.bins, (new_min, new_max))
         else:
-            new_min = x.min()
-            new_max = x.max()
-            combined_min = min(new_min, min_val)
-            combined_max = max(new_max, max_val)
+            new_min = min(new_min, min_val)
+            new_max = max(new_max, max_val)
             # combine the existing histogram and new histogram into 1 histogram
             # We do this by first upsampling the histogram to a dense grid
             # and then downsampling the histogram efficiently
-            (
-                combined_min,
-                combined_max,
-                downsample_rate,
-                start_idx,
-            ) = self._adjust_min_max(combined_min, combined_max, self.upsample_rate)
-
-            combined_histogram, _ = np.histogram(
-                x, self.bins, (combined_min, combined_max)
+            (new_min, new_max, downsample_rate, start_idx,) = self._adjust_min_max(
+                new_min, new_max, self.upsample_rate
             )
-            combined_histogram = combined_histogram.astype(np.float64)
-            if combined_min == min_val and combined_max == max_val:
-                combined_histogram += self.histogram
+
+            new_histogram, _ = np.histogram(x, self.bins, (new_min, new_max))
+            new_histogram = new_histogram.astype(np.float64)
+            if new_min == min_val and new_max == max_val:
+                new_histogram += histogram
             else:
-                combined_histogram = self._combine_histograms(
-                    combined_histogram,
-                    self.histogram,
+                new_histogram = self._combine_histograms(
+                    new_histogram,
+                    histogram,
                     self.upsample_rate,
                     downsample_rate,
                     start_idx,
                     self.bins,
                 )
-            self.histogram = combined_histogram
-            self.min_val.set_value(combined_min)
-            self.max_val.set_value(combined_max)
+
+        self.histogram.set_value(new_histogram)
+        self.min_val.set_value(new_min)
+        self.max_val.set_value(new_max)
 
     def forward(self, x_orig):
         self.sideeffect_forward(x_orig)