[skip-ci] Add benchmarks for Dataset binary ops, chunk (#8351)

xref #8339
xref #8350

asv_bench/benchmarks/dataset.py

@@ -0,0 +1,32 @@
+import numpy as np
+
+from xarray import Dataset
+
+from . import requires_dask
+
+
+class DatasetBinaryOp:
+    def setup(self):
+        self.ds = Dataset(
+            {
+                "a": (("x", "y"), np.ones((300, 400))),
+                "b": (("x", "y"), np.ones((300, 400))),
+            }
+        )
+        self.mean = self.ds.mean()
+        self.std = self.ds.std()
+
+    def time_normalize(self):
+        (self.ds - self.mean) / self.std
+
+
+class DatasetChunk:
+    def setup(self):
+        requires_dask()
+        self.ds = Dataset()
+        array = np.ones(1000)
+        for i in range(250):
+            self.ds[f"var{i}"] = ("x", array)
+
+    def time_chunk(self):
+        self.ds.chunk(x=(1,) * 1000)