fix test_poisson UT (#43315)

python/paddle/fluid/tests/unittests/test_poisson_op.py

@@ -45,8 +45,8 @@ class TestPoissonOp1(OpTest):
         self.config()
 
         self.attrs = {}
-        self.inputs = {'X': np.full([1024, 1024], self.lam, dtype=self.dtype)}
-        self.outputs = {'Out': np.ones([1024, 1024], dtype=self.dtype)}
+        self.inputs = {'X': np.full([2048, 1024], self.lam, dtype=self.dtype)}
+        self.outputs = {'Out': np.ones([2048, 1024], dtype=self.dtype)}
 
     def config(self):
         self.lam = 10
@@ -66,9 +66,9 @@ class TestPoissonOp1(OpTest):
         self.check_grad(
             ['X'],
             'Out',
-            user_defined_grads=[np.zeros([1024, 1024], dtype=self.dtype)],
+            user_defined_grads=[np.zeros([2048, 1024], dtype=self.dtype)],
             user_defined_grad_outputs=[
-                np.random.rand(1024, 1024).astype(self.dtype)
+                np.random.rand(2048, 1024).astype(self.dtype)
             ])
 
 
@@ -77,7 +77,7 @@ class TestPoissonOp2(TestPoissonOp1):
     def config(self):
         self.lam = 5
         self.a = 1
-        self.b = 9
+        self.b = 8
         self.dtype = "float32"