Adel Johar
166 рядки
5.0 KiB
ReStructuredText
166 рядки
5.0 KiB
ReStructuredText
.. meta::
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:description: RCCL is a stand-alone library that provides multi-GPU and multi-node collective communication primitives optimized for AMD GPUs
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:keywords: RCCL, ROCm, library, API, reference, environment variable, environment
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.. _env-variables:
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********************************************************************
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RCCL environment variables
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********************************************************************
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This section describes the most important RCCL environment variables,
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which are grouped by functionality.
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Configuration and setup
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========================
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The configuration and setup environment variables for RCCL are collected
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in the following table.
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.. list-table::
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:header-rows: 1
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:widths: 70,30
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* - **Environment variable**
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- **Value**
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* - | ``NCCL_CONF_FILE``
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| Specifies the path to the RCCL configuration file.
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- | String path to configuration file
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| Default: ``~/.rccl.conf`` or ``/etc/rccl.conf``
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* - | ``NCCL_HOSTID``
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| Sets the host identifier for multi-node communication.
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- | String value for host identification
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| Used for host hash generation
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Logging and debugging
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=====================
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The logging and debugging environment variables for RCCL are collected
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in the following table.
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.. list-table::
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:header-rows: 1
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:widths: 70,30
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* - **Environment variable**
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- **Value**
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* - | ``RCCL_LOG_LEVEL``
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| Controls RCCL logging verbosity.
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- | Integer value (default: ``1``)
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| Higher values increase logging detail
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* - | ``NCCL_DEBUG_SUBSYS``
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| Controls which subsystems generate debug output.
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- | Comma-separated list of subsystems (e.g., ``INIT,COLL``)
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| Prefix with ``^`` to invert selection
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Algorithm and protocol control
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==============================
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The algorithm and protocol control environment variables for RCCL are
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collected in the following table.
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.. list-table::
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:header-rows: 1
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:widths: 70,30
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* - **Environment variable**
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- **Value**
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* - | ``NCCL_ALGO``
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| Forces specific algorithm selection for collectives.
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- | Algorithm name string
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| Used to override automatic algorithm selection
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* - | ``NCCL_PROTO``
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| Forces specific protocol selection for communication.
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- | Protocol name string
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| Used to override automatic protocol selection
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Network and topology
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====================
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The network and topology environment variables for RCCL are collected
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in the following table.
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.. list-table::
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:header-rows: 1
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:widths: 70,30
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* - **Environment variable**
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- **Value**
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* - | ``NCCL_IB_HCA``
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| Specifies InfiniBand device:port to use.
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- | Device specification string
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| Prefix with ``^`` for exclusion, ``=`` for exact match
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* - | ``NCCL_IB_GID_INDEX``
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| Defines the Global ID index used in RoCE mode.
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- | Integer value (default: ``-1``)
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| See InfiniBand ``show_gids`` command for valid values
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* - | ``NCCL_SOCKET_IFNAME``
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| Specifies which IP interfaces to use for communication.
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- | Interface prefix string or list
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| Multiple prefixes separated by ``,``
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| Prefix with ``^`` for exclusion, ``=`` for exact match
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| Example: ``eth`` (all eth interfaces), ``=eth0`` (exact match)
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* - | ``NCCL_SOCKET_FAMILY``
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| Forces IPv4/IPv6 interface selection.
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- | ``AF_INET``: Force IPv4
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| ``AF_INET6``: Force IPv6
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| Unset: Use first available
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* - | ``NCCL_NET_MERGE_LEVEL``
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| Controls network device merging behavior.
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- | Integer value specifying merge level
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| Default: ``PATH_PORT``
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* - | ``NCCL_NET_FORCE_MERGE``
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| Forces merging of network devices.
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- | String specifying forced merge configuration
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* - | ``NCCL_RINGS``
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| Defines custom ring topology.
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- | Ring topology specification string
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| Overrides automatic topology detection
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* - | ``RCCL_TREES``
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| Defines custom tree topology.
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- | Tree topology specification string
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| Alternative to ring topology
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* - | ``NCCL_RINGS_REMAP``
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| Controls ring remapping for specific topologies.
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- | Remapping specification string
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| Used with Rome 4P2H topology
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Development and testing (advanced)
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==================================
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The development and testing environment variables for RCCL are
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collected in the following table. These variables are primarily
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intended for debugging and development purposes.
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.. list-table::
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:header-rows: 1
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:widths: 70,30
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* - **Environment variable**
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- **Value**
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* - | ``CUDA_LAUNCH_BLOCKING``
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| Controls CUDA kernel launch blocking behavior.
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- | ``0``: Non-blocking launches
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| ``1`` or non-zero: Blocking launches
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* - | ``NCCL_COMM_ID``
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| Enables multi-process mode in test applications.
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- | Any non-empty value enables multi-process mode
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| Used with test executables for distributed testing
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