[Bug]: 'no module 'xformers'. Processing without' on fresh installation of v1.9.0 about stable-diffusion-webui

[w-e-w]

I ask around and it seems that xformers dose work on linux, but one who replyed me is dose not know about installing via the webui arg --xformers, insted he installed xformers using pip due to Cannot find ptxas

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I think what you are seeing it's a bit odd
you can see in the logs that xformers, and theres no error showing that the install has failed
but later you see webui can't import xformers

at this point I would first try again, if that dose not work try installing the latest version of xformers

---

tip when posting logs or code like above use a code block

```
you logs
``` 

[w-e-w]

add --xformers arg to webui.sh

[TommyQTran]

@w-e-w I get a Cannot find ptxas Runtime Error.

Installing xformers
Launching Web UI with arguments: --xformers
no module 'xformers'. Processing without...
no module 'xformers'. Processing without...
No module 'xformers'. Proceeding without it.
*** Cannot import xformers
    Traceback (most recent call last):
      File "/stable-diffusion-webui/modules/sd_hijack_optimizations.py", line 160, in <module>
        import xformers.ops
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/xformers/ops/__init__.py", line 8, in <module>
        from .fmha import (
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/xformers/ops/fmha/__init__.py", line 10, in <module>
        from . import attn_bias, cutlass, decoder, flash, small_k, triton, triton_splitk
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/xformers/ops/fmha/triton_splitk.py", line 21, in <module>
        if TYPE_CHECKING or _has_triton21():
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/xformers/ops/common.py", line 192, in _has_triton21
        if not _has_a_version_of_triton():
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/xformers/ops/common.py", line 176, in _has_a_version_of_triton
        import triton  # noqa: F401
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/triton/__init__.py", line 20, in <module>
        from .compiler import compile, CompilationError
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/triton/compiler/__init__.py", line 1, in <module>
        from .compiler import CompiledKernel, compile, instance_descriptor
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/triton/compiler/compiler.py", line 27, in <module>
        from .code_generator import ast_to_ttir
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/triton/compiler/code_generator.py", line 8, in <module>
        from .. import language
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/triton/language/__init__.py", line 4, in <module>
        from . import math
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/triton/language/math.py", line 4, in <module>
        from . import core
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/triton/language/core.py", line 1376, in <module>
        def minimum(x, y):
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/triton/runtime/jit.py", line 542, in jit
        return decorator(fn)
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/triton/runtime/jit.py", line 534, in decorator
        return JITFunction(
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/triton/runtime/jit.py", line 433, in __init__
        self.run = self._make_launcher()
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/triton/runtime/jit.py", line 388, in _make_launcher
        scope = {"version_key": version_key(),
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/triton/runtime/jit.py", line 120, in version_key
        ptxas = path_to_ptxas()[0]
      File "/stable-diffusion-webui/venv/lib/python3.10/site-packages/triton/common/backend.py", line 119, in path_to_ptxas
        raise RuntimeError("Cannot find ptxas")
    RuntimeError: Cannot find ptxas

[w-e-w]

I'm on windows so I'm not sure how it's is on windwos
but base on info on our wiki xformers shoud work on linux
not sure if anything has changed

[TommyQTran]

I solved this by creating a pyenv virtualenv.

pyenv virtualenv <name>
pyenv activate <name>

[Gavin-Evans]

reference #15444