update bnb log

[jiqing-feng]

Update the error message when xpu is available, we don't need native library on XPU
@matthewdouglas Please review it. Thanks!

[yao-matrix]

why need ErrorHandlerMockBNBNativeLibrary

[jiqing-feng]

I thought it was the default lib, but we can just set lib=None since XPU will not use lib.

[Devjiu]

Can we please mention Triton here?
For example: "XPU is detected, but IPEX is missing, will try to use Trtiton implementation. If performance is lower your expectations, consider installing IPEX"

The current wording effectively prohibits the use of XPU without IPEX.

[jiqing-feng]

fixed

[github-actions]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[jiqing-feng]

We need to use mock lib because of the functional variable.

[jiqing-feng]

Hi @matthewdouglas . This PR is ready to be reviewed, please let me know your comments. Thanks!

[Egor-Krivov]

I don't think we should push user into a specific XPU backend, until we clearly know which one is likely faster.
I just run simple inference benchmark and couldn't get performance improvements from IPEX: #1629 (comment)

[jiqing-feng]

I don't think we should push user into a specific XPU backend, until we clearly know which one is likely faster. I just run simple inference benchmark and couldn't get performance improvements from IPEX: #1629 (comment)

You were right, I have changed the log. This PR will avoid xpu through load native library error, as we don't want to load native lib on XPU. Please review my new changes. Without this PR, the error be like:

Traceback (most recent call last):
  File "/usr/local/lib/python3.11/dist-packages/bitsandbytes/cextension.py", line 115, in <module>
    lib = get_native_library()
          ^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/dist-packages/bitsandbytes/cextension.py", line 86, in get_native_library
    dll = ct.cdll.LoadLibrary(str(binary_path))
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/ctypes/__init__.py", line 454, in LoadLibrary
    return self._dlltype(name)
           ^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/ctypes/__init__.py", line 376, in __init__
    self._handle = _dlopen(self._name, mode)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^
OSError: /usr/local/lib/python3.11/dist-packages/bitsandbytes/libbitsandbytes_cpu.so: cannot open shared object file: No such file or directory

[matthewdouglas]

Wouldn't we still want it in case the user has a reason to use the two CPU ops it implements? We don't necessarily know they won't just because an XPU is available.

[matthewdouglas]

For most of our target audience I feel like this isn't going to be super informative. It's OK for now but eventually we might want to find a way to spell out exactly what it means for them, and whether we should be loud about it or not.

[jiqing-feng]

Close this PR as we may change the XPU behavior in the future.