py3nvml 0.2.7
Python 3 Bindings for the NVIDIA Management Library
License: BSD

py3nvml
=======
Documentation also available at `readthedocs`__.

Python 3 compatible bindings to the NVIDIA Management Library. Can be used to
query the state of the GPUs on your system. This was ported from the NVIDIA
provided python bindings `nvidia-ml-py`__, which only 
supported python 2. I have forked from version 7.352.0. The old library was 
itself a wrapper around the `NVIDIA Management Library`__.

__ https://py3nvml.readthedocs.io/en/latest/
__ https://pypi.python.org/pypi/nvidia-ml-py/7.352.0
__ http://developer.nvidia.com/nvidia-management-library-nvml

In addition to these NVIDIA functions to query the state of the GPU, I have written
a couple functions/tools to help in using gpus (particularly for a shared
gpu server). These are:

- A function to 'restrict' the available GPUs by setting the `CUDA_VISIBLE_DEVICES` 
  environment variable. 
- A script for displaying a differently formatted nvidia-smi.

See the Utils section below for more info.

Updates in Version 0.2.3
------------------------
To try and keep py3nvml somewhat up-to-date with the constantly evolving nvidia
drivers, I have done some work to the `py3nvml.py3nvml` module. In particular,
I have updated all the constants that were missing in py3nvml and existing in the
`NVIDIA source`__ as of version 418.43. In addition, I have wrapped all of these 
constants in Enums so it is easier to see what constants go together. Finally,
for all the functions in `py3nvml.py3nvml` I have copied in the
C docstring. While this will result in some strange looking docstrings which
will be slightly incorrect, they should give good guidance on the scope of the
function, something which was ill-defined before.

Finally, I will remove the `py3nvml.nvidia_smi` module in a future version, as
I believe it was only ever meant as an example of how to use the nvml functions
to query the gpus, and is now quite out of date. To get the same functionality,
you can call `nvidia-smi -q -x` from python with subprocess.

__ https://github.com/NVIDIA/nvidia-settings/blob/master/src/nvml.h

Requires
--------
Python 3.5+.

Installation 
------------
From PyPi::

    $ pip install py3nvml

From GitHub::
    
    $ pip install -e git+https://github.com/fbcotter/py3nvml#egg=py3nvml

Or, download and pip install:: 

    $ git clone https://github.com/fbcotter/py3nvml
    $ cd py3nvml
    $ pip install .

.. _utils-label:

Utils 
-----
(Added by me - not ported from NVIDIA library)

grab_gpus
~~~~~~~~~

You can call the :code:`grab_gpus(num_gpus, gpu_select, gpu_fraction=.95)` function to check the available gpus and set
the `CUDA_VISIBLE_DEVICES` environment variable as need be. It determines if a GPU is available by checking if the
amount of free memory is below memory-usage is above/equal to the gpu_fraction value. The default of .95 allows for some
small amount of memory to be taken before it deems the gpu as being 'used'. 

I have found this useful as I have a shared gpu server and like to use tensorflow which is very greedy and calls to
:code:`tf.Session()` grabs all available gpus.

E.g.

.. code:: python

    import py3nvml
    import tensorflow as tf
    py3nvml.grab_gpus(3)
    sess = tf.Session() # now we only grab 3 gpus!

Or the following will grab 2 gpus from the first 4 (and leave any higher gpus untouched)

.. code:: python
    
    py3nvml.grab_gpus(num_gpus=2, gpu_select=[0,1,2,3])
    sess = tf.Session() 

This will look for 3 available gpus in the range of gpus from 0 to 3. The range option is not necessary, and it only
serves to restrict the search space for the grab_gpus. 

You can adjust the memory threshold for determining if a GPU is free/used with the :code:`gpu_fraction` parameter
(default is 1):

.. code:: python
    
    # Will allocate a GPU if less than 20% of its memory is being used
    py3nvml.grab_gpus(num_gpus=2, gpu_fraction=0.8)
    sess = tf.Session() 

You can select the graphics card based on its capacity. Specify minimal amount of graphics card memory in MiB in 
order to exclude the weaker graphics cards.

.. code:: python
    
    # Will allocate a GPU only if it has more than 4000 MiB of memory
    py3nvml.grab_gpus(num_gpus=2, gpu_min_memory=4000)
    sess = tf.Session() 

This function has no return codes but may raise some warnings/exceptions:

- If the method could not connect to any NVIDIA gpus, it will raise
  a RuntimeWarning. 
- If it could connect to the GPUs, but there were none available, it will 
  raise a ValueError. 
- If it could connect to the GPUs but not enough were available (i.e. more than
  1 was requested), it will take everything it can and raise a RuntimeWarning.

get_free_gpus
~~~~~~~~~~~~~
This tool can query the gpu status. Unlike the default for `grab_gpus`, which checks the memory usage of a gpu, this
function checks if a process is running on a gpu. For a system with N gpus, returns a list of N booleans, where the nth
value is True if no process was found running on gpu n. An example use is:

.. code:: python
    
    import py3nvml
    free_gpus = py3nvml.get_free_gpus()
    if True not in free_gpus:
        print('No free gpus found')

get_num_procs
~~~~~~~~~~~~~
This function is called by `get_free_gpus`. It simply returns a list of integers
with the number of processes running on each gpu. E.g. if you had 1 process
running on gpu 5 in an 8 gpu system, you would expect to get the following:

.. code:: python
    
    import py3nvml
    num_procs = py3nvml.get_num_procs()
    print(num_proces)
    >>> [0, 0, 0, 0, 0, 1, 0, 0]

py3smi
~~~~~~
I found the default `nvidia-smi` output was missing some useful info, so made use of the
`py3nvml/nvidia_smi.py` module to query the device and get info on the
GPUs, and then defined my own printout. I have included this as a script in
`scripts/py3smi`. The print code is horribly messy but the query code is very
simple and should be understandable. 

Running pip install will now put this script in your python's
bin, and you'll be able to run it from the command line. Here is a comparison of
the two outputs:

.. image:: https://i.imgur.com/TvdfkFE.png

.. image:: https://i.imgur.com/UPSHr8k.png

For py3smi, you can specify an update period so it will refresh the feed every
few seconds. I.e., similar to :code:`watch -n5 nvidia-smi`, you can run
:code:`py3smi -l 5`.

You can also get the full output (very similar to nvidia-smi) by running `py3smi
-f` (this shows a slightly modified process info pane below).

Regular Usage 
-------------
Visit `NVML reference`__ for a list of the
functions available and their help. Also the script py3smi is a bit hacky but
shows examples of me querying the GPUs for info. 

__ https://docs.nvidia.com/deploy/nvml-api/index.html

(below here is everything ported from pynvml)

.. code:: python

    from py3nvml.py3nvml import *
    nvmlInit()
    print("Driver Version: {}".format(nvmlSystemGetDriverVersion()))
    # e.g. will print:
    #   Driver Version: 352.00
    deviceCount = nvmlDeviceGetCount()
    for i in range(deviceCount):
        handle = nvmlDeviceGetHandleByIndex(i)
        print("Device {}: {}".format(i, nvmlDeviceGetName(handle)))
    # e.g. will print:
    #  Device 0 : Tesla K40c
    #  Device 1 : Tesla K40c
    
    nvmlShutdown()

Additionally, see `py3nvml.nvidia_smi.py`. This does the equivalent of the
`nvidia-smi` command:: 

    nvidia-smi -q -x

With

.. code:: python

    import py3nvml.nvidia_smi as smi
    print(smi.XmlDeviceQuery())

Differences from NVML
~~~~~~~~~~~~~~~~~~~~~
The py3nvml library consists of python methods which wrap 
several NVML functions, implemented in a C shared library.
Each function's use is the same with the following exceptions:

1. Instead of returning error codes, failing error codes are raised as Python exceptions. I.e. They should be wrapped with exception handlers.

  .. code:: python

    try:
        nvmlDeviceGetCount()
    except NVMLError as error:
        print(error)


2. C function output parameters are returned from the corresponding Python function as tuples, rather than requiring pointers. Eg the C function:
    
  .. code:: c

    nvmlReturn_t nvmlDeviceGetEccMode(nvmlDevice_t device,
                                      nvmlEnableState_t *current,
                                      nvmlEnableState_t *pending);

  Becomes

  .. code:: python

    nvmlInit()
    handle = nvmlDeviceGetHandleByIndex(0)
    (current, pending) = nvmlDeviceGetEccMode(handle)

3. C structs are converted into Python classes. E.g. the C struct:

  .. code:: c

    nvmlReturn_t DECLDIR nvmlDeviceGetMemoryInfo(nvmlDevice_t device,
                                                 nvmlMemory_t *memory);
    typedef struct nvmlMemory_st {
        unsigned long long total;
        unsigned long long free;
        unsigned long long used;
    } nvmlMemory_t;

  Becomes:

  .. code:: python

    info = nvmlDeviceGetMemoryInfo(handle)
    print("Total memory: {}MiB".format(info.total >> 20))
    # will print:
    #   Total memory: 5375MiB
    print("Free memory: {}".format(info.free >> 20))
    # will print:
    #   Free memory: 5319MiB
    print("Used memory: ".format(info.used >> 20))
    # will print:
    #   Used memory: 55MiB

4. Python handles string buffer creation.  E.g. the C function:

  .. code:: c

    nvmlReturn_t nvmlSystemGetDriverVersion(char* version,
                                            unsigned int length);

  Can be called like so:

  .. code:: python

    version = nvmlSystemGetDriverVersion()
    nvmlShutdown()


5.  All meaningful NVML constants and enums are exposed in Python. E.g. the constant `NVML_TEMPERATURE_GPU` is available under
`py3nvml.NVML_TEMPERATURE_GPU` 

The `NVML_VALUE_NOT_AVAILABLE` constant is not used.  Instead None is mapped to the field.

Release Notes (for pynvml)
--------------------------
Version 2.285.0

- Added new functions for NVML 2.285.  See NVML documentation for more information.
- Ported to support Python 3.0 and Python 2.0 syntax.
- Added nvidia_smi.py tool as a sample app.

Version 3.295.0

- Added new functions for NVML 3.295.  See NVML documentation for more information.
- Updated nvidia_smi.py tool
  - Includes additional error handling

Version 4.304.0

- Added new functions for NVML 4.304.  See NVML documentation for more information.
- Updated nvidia_smi.py tool

Version 4.304.3

- Fixing nvmlUnitGetDeviceCount bug

Version 5.319.0

- Added new functions for NVML 5.319.  See NVML documentation for more information.

Version 6.340.0

- Added new functions for NVML 6.340.  See NVML documentation for more information.

Version 7.346.0

- Added new functions for NVML 7.346.  See NVML documentation for more information.

Version 7.352.0

- Added new functions for NVML 7.352.  See NVML documentation for more information.

COPYRIGHT
---------
Copyright (c) 2011-2015, NVIDIA Corporation.  All rights reserved.

LICENSE
-------
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

- Redistributions of source code must retain the above copyright notice, this
  list of conditions and the following disclaimer.

- Redistributions in binary form must reproduce the above copyright notice,
  this list of conditions and the following disclaimer in the documentation
  and/or other materials provided with the distribution.

- Neither the name of the NVIDIA Corporation nor the names of its contributors
  may be used to endorse or promote products derived from this software without
  specific prior written permission.

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