Added triton test.

tests/test_triton.py

+import pytest
+import torch
+
+from bitsandbytes.nn.triton_based_modules import SwitchBackLinear, SwitchBackGlobalLinear
+
+
+
+@pytest.mark.parametrize("triton_module", [SwitchBackGlobalLinear, SwitchBackLinear])
+def test_switchbatch(triton_module):
+    for dim in [83, 17, 128]:
+        for batch in [13, 128, 256]:
+
+            standard = torch.nn.Linear(dim, 4 * dim).cuda().half()
+            switchback = triton_module(dim, 4 * dim).cuda().half()
+            switchback.weight.data.copy_(standard.weight)
+            switchback.bias.data.copy_(standard.bias)
+
+
+            for i in range(100):
+                x1 = torch.randn(batch, dim).cuda().half().requires_grad_(True)
+                x2 = x1.clone().detach().requires_grad_(True)
+                print('standard')
+                out_standard = standard(x1)
+                print('switchback')
+                out_sb = switchback(x1)
+
+                (out_standard.abs().mean()).backward()
+                (out_sb.abs().mean()).backward()
+
+                err_sb = (out_standard - out_sb).abs().mean()
+                print('OUT', err_sb)
+
+                err_sb = (standard.bias.grad - switchback.bias.grad).abs().mean()
+
+                print('GW2', err_sb)
+
+                err_sb = (standard.weight.grad - switchback.weight.grad).abs().mean()
+
+                print('GW1', err_sb)
+
+                #err_sb = (x1.grad - x2.grad).abs().mean()
+
+                #print('GX1', err_sb)
+