6 커밋

작성자	SHA1	메시지	날짜
Mark Santesson	f1308997d0	NCCL 2.28.3-1 ... Device API (Experimental) * Introduces device-side APIs to integrate NCCL communication directly into application kernels. * Supports LSA (Load/Store Access) for CUDA P2P communication over NVLink and some PCIe platforms. * Supports Multimem for hardware multicast using NVLink SHARP. * Adds initial framework for GIN (GPU-Initiated Networking), currently under development. * Introduces device communicators created using ncclDevCommCreate. * Enables device-side communication operations with synchronization (ncclLsaBarrierSession) and memory accessors (ncclGetLsaPointer, ncclGetLsaMultimemPointer). * Experimental APIs - signatures and functionality may evolve in future releases. * No ABI compatibility is guaranteed — applications must be recompiled with each new NCCL release. Symmetric memory improvements * Support for aggregating symmetric operations using ncclGroupStart/End APIs. * Reimplement symmetric kernels using device API. New Host APIs * Introduce new host collective APIs: ncclAlltoAll, ncclScatter, ncclGather. CE (Copy Engine) Collectives * Reduce SM utilization for alltoall, scatter, gather, and allgather within a single (MN)NVL domain. * Free up SM capacity for the application to do computation at the same time. * To enable the feature for ncclAllGather, ncclAlltoAll, ncclGather, ncclScatter, register buffers into symmetric windows and use the NCCL_CTA_POLICY_ZERO flag in the communicator config_t. NCCL Inspector Plugin * Introduces an Inspector plugin for always-on performance monitoring. * Produces structured JSON output with metadata, execution time, bandwidth, and optional event traces for each NCCL operation. * Enables integration with analysis tools such as Performance Exporter to visualize NCCL performance bottlenecks. * Lightweight to enable via environment variables NCCL_PROFILER_PLUGIN and NCCL_INSPECTOR_ENABLE. CMake support (Experiemental) * Adds a CMake build system as an alternative to existing Makefiles. * Known issues: pkg.build and Device API currently do not work with CMake. * The known issues will be addressed in a future release. Decreased max CTA count from 32 to 16 on Blackwell * SM overhead is decreased by 50% with this improvement. * This may cause some perf drop on Blackwell because of the reduced SM usage. * If the extra SM capacity is not desired, two options are available to restore to previous behavior: 1) Setting NCCL_MIN_CTAS=32 NCCL_MAX_CTAS=32 environment variables; 2) setting communicator config to over-write max CTA count to 32. * Based on community feedback, future versions may consider different trade-offs between performance and SM overhead. Plugins * Network * App-aware Network plugin. NCCL passes information about communication operations to be executed on the network end point. This allows for better tuning of network end points and their use in the plugins. * Improve handling of physical and virtual network devices and load/unload. * Network plugin version 11 - add explicit context and communication ID support for per communicator init/finalize. * Add Multi-Request Net API. Using this will help NCCL to anticipate multiple send/recv requests and optimize for it. See maxMultiRequestSize field in ncclNetProperties_v11_t. * Profiler * Add support for API events (group, collective, and p2p) and for tracking kernel launches in the profiler plugin. * Add Inspector Profiler Plugin (see section above). * Add a hook to Google’s CoMMA profiler on github. * Tuner * Expose NCCL tuning constants at tuner initialization via ncclTunerConstants_v5_t. * Add NVL Domain Information API. * Support multiple plugin types from a single shared object. New Parameterization and ncclConfig changes: * Add new option NCCL_MNNVL_CLIQUE_ID=-2 which will use rack serial number to partition the MNNVL clique. This will limit NVLink domains to GPUs within a single rack. * Add NCCL_NETDEVS_POLICY to control how NET devices are assigned to GPUs. The default (AUTO) is the policy used in previous versions. * Add NCCL_SINGLE_PROC_MEM_REG_ENABLE control variable to enable NVLS UB registration in the “one process, multiple ranks” case as opt in. * Move nChannelsPerNetPeer into ncclConfig. NCCL_NCHANNELS_PER_NET_PEER can override the value in ncclConfig. * Enable PxN over C2C by default * PxN over C2C will improve performance for Grace-Blackwell platforms by allowing NCCL to leverage the NIC attached to a peer GPU over NVLINK, C2C, and PCIe. * This behavior can be overridden by setting NCCL_PXN_C2C=0. Other Improvements: * Allow FP8 support for non-reductive operations on pre sm90 devices. (See https://github.com/pytorch/pytorch/pull/151594#discussion_r2135777776) * Fix NVLS+CollNet and temporarily disables COLLNET_CHAIN for >8 GPUs. * Only consider running interfaces for socket traffic. NCCL will not attempt to use interfaces that do not have the IFF_RUNNING bit. (https://github.com/NVIDIA/nccl/issues/1798) * Modernize mutex management. Convert to std::mutex and std::lock_guard. * Remove sm35 and sm50 GENCODE targets which have long been deprecated and were causing issues with the latest NCCL release builds. * Improved NVLS/NVLSTree tuning prediction to improve algorithm and protocol selection. * NVLSTree Tuning Fixes. Update tuning data for H100, GB200-NV72. * Respond better to RoCE link flaps. Instead of reporting an “unknown event” it will now report “GID table changed”. * Move libvirt bridge interface to the end of possible interfaces so that they are considered last. These interfaces are usually virtual bridges to relay traffic to containers running on the host and cannot be used for traffic to a remote node and are therefore unsuitable.	2025-09-02 13:53:34 -07:00
Kamil Iskra	f44ac759fe	NCCL 2.26.2-1 ... Profiler improvements * Add events for CUDA kernel start and end. * Allow network plugins to generate profiling events * Enable profiling on a per-operation basis, rather than per-communicator. * Add support for graph capturing. Add implicit launch order * Allow to prevent deadlocks when using multiple NCCL communicators per device by implicitly ordering NCCL operations using the host program order. Disabled by default, set NCCL_LAUNCH_ORDER_IMPLICIT=1 to enable. * Add a complementary mechanism to detect host threads racing to launch to the same device. Enabled by default, set NCCL_LAUNCH_RACE_FATAL=0 to disable. Optimize the PAT algorithm * Separate the computation and execution of PAT steps on different warps, allowing to run up to 16 PAT steps in parallel to significantly accelerate PAT and reduce its linear part. Add support for setting QoS per communicator * Add a new trafficClass field to the communicator configuration, to allow the application to select a particular traffic class for a given communicator. The meaning of the traffic class is network-specific and should be set in accordance with the network configuration. * For the IB/RoCE plugin, existing config variables such as NCCL_IB_SL and NCCL_IB_TC take precedence. Allow to enable GPU Direct RDMA specifically on C2C platforms * Disabled by default, set NCCL_NET_GDR_C2C=1 to enable. Do not disable user buffer registration unless PXN is really used * Only disable UB when a communicator has more than one rank per node on any node. RAS subsystem improvements * Report operation counts separately for each collective operation type. * Provide details about missing communicator ranks and reliably distinguish ranks that are no longer a given communicator's members (now reported as NOCOMM) from those that failed to respond. Add support for timestamps to NCCL diagnostic messages * On by default for WARN messages; NCCL_DEBUG_TIMESTAMP_LEVELS can be used to enable them for other debug levels as well. * The format can be changed using the NCCL_DEBUG_TIMESTAMP_FORMAT config variable. Reduce the memory usage with NVLink SHARP (NVLS) * Potentially save hundreds of MBs of device memory, considering the multicast buffer size granularity separately from the address alignment. Update performance tuning for recent Intel CPUs * Improve algorithm/protocol selection on recent CPUs such as Emerald Rapids and Sapphire Rapids. Improve channel scheduling when mixing LL and Simple operations. * Make LL operations account for 4x more traffic to ensure LL and simple operations complete at the same time. Refactor the plugin code * Clean up and harmonize the support code across the network, tuner, and profiler plugins. Add support for comment lines (starting with #) in the nccl.conf file * Issue #1540. Make user buffer registration problems print an INFO instead of a WARN. Drop support for network plugin interface version 5. Fix a race condition with split-shared communicators * NCCL could hang during connection setup if multiple communicators were grouped together that share resources. Fix a performance regression when using NCCL_CROSS_NIC=1 * NCCL would unnecessarily alternate rings, breaking the GPU-NIC associations. Make GID index detection code more resilient * Dynamic GID detection code was giving up too soon if the detected index was not available (e.g., wasn't mapped to the container's sysfs). * Issues #1538, #1573. Fix a race condition with non-blocking operation * Fix issue when creating a non-blocking communicator after a non- blocking collective operation on another communicator. Fix shared memory usage on recent Blackwell GPUs. * Issues NVIDIA/nccl-tests#287, NVIDIA/nccl-tests#291, #1637. Fix an error with NIC fusion and IB SHARP when recreating communicators * Disable the unloading of network plugins Make the auto-merge failures in the NIC fusion non-fatal * This could happen when trying to merge IB and RoCE devices. Fixes to ncclCommAbort * Fix hangs due to the progress thread spinning indefinitely on the network progress. * Reduce the abort time by up to two orders of magnitude. Fix a crash when libnccl.so was dynamically unloaded * The RAS subsystem was missing a clean-up handler. Fix a hang if the network plugin's test() call returns an error. Fix a hang on heterogeneous architectures * Ensure we harmonize the tuning to avoid different tuning choices, causing a hang. Fix double-free on failed ncclCommInitRank and ncclCommFinalize. Fix a potential list traversal bug during a group launch of multiple communicators * Issue #1599. Unify the handling of NCCL configuration variables * Under rare circumstances, some variables specified in the config file could be ignored.	2025-03-12 13:46:21 -07:00
Sylvain Jeaugey	6aae379278	2.24.3-1 ... Network user buffer support for collectives * Leverage user buffer registration to achieve zero-copy inter-node communications for Ring, NVLS and Collnet Add RAS subsystem * Create a RAS thread keeping track of all NCCL communicators. * Add a ncclras tool contacting the RAS thread and getting a report. Add fp8 support * Add support for e5m2 and e4m3 8-bit floating point operations. * Use Tree/PAT algorithms when possible for better numerical stability. Add NIC fusion * Add a NET API to ask the network plugin to fuse a set of interfaces together. * Fuse multiple NICs under the same PCI switch as a single, larger NIC. Socket connection failure retry * Retry in case of socket connection failure (unreachable host) * Avoid "Software caused connection abort" errors on retries QP connection failure retry * Retry in case of IB QP connection failure during ibv_modify_qp. NET API improvements * Allow plugins to force a flush in case data and completion ordering is not guaranteed. * Indicate when completion is not needed (e.g. for the LL128 protocol), allowing plugins to skip generating a completion. * Allow for full offload of allgather operations when using one GPU per node. NCCL_ALGO/NCCL_PROTO strict enforcement * Extend NCCL_ALGO/NCCL_PROTO syntax to be able to specify ALGO/PROTO filters for each collective operation. * Strictly enforce the ALGO/PROTO filters, no longer fall back on the ring algorithm when the filtering leaves no option and error out instead. Enable CUMEM host allocations * Use cumem functions for host memory allocation by default. Improved profiler plugin API * Avoid dependencies with NCCL includes. * Add information on whether the buffer is registered or not Adjust PAT tuning * Improve transition between PAT and ring at scale. Fix hangs when running with different CPU architectures * Detect when we use a mix of GPU architectures * Ensure Algo/Proto decisions are made based on that unified state. Fix FD leak in UDS * Fix a leak when mapping buffers intra-node with cumem IPCs. Fix crash when mixing buffer registration and graph buffer registration. * Separate local and graph registration to avoid crashes when we free buffers. Fix user buffer registration with dmabuf * Make ncclSend/ncclRecv communication with buffer registration functional on network plugins relying on dmabuf for buffer registration. Fix crash in IB code caused by uninitialized fields. Fix non-blocking ncclSend/ncclRecv * Fix case where ncclSend/ncclRecv would return ncclSuccess in non-blocking mode even though the operation was not enqueued onto the stream. * Issue #1495 Various compiler tweaks and fixes * PR #758 Fix typo in ncclTopoPrintGraph * Issue #1468	2025-01-07 02:01:15 -08:00
Sylvain Jeaugey	b6475625fb	2.20.3-1 ... Add support for alternating rings, allow for cross-nic rings without cross-rail communication. Add support for user buffer registration for network send/recv. Optimize aggregated operations to better utilize all channels. Add flattening for BCM PCI gen5 switches. Add support for inter-node NVLink communication Add support for port fusion in NET/IB. Add support for ReduceScatter and AllGather using Collnet. Update net API to v8. Fix hang during A2A connection.	2024-02-13 04:22:38 -08:00
Sylvain Jeaugey	f9c3dc251e	2.19.1-1 ... Add local user buffer registration for NVLink SHARP. Add tuning plugin support. Increase net API to v7 to allow for device-side packet reordering; remove support for v4 plugins. Add support for RoCE ECE. Add support for C2C links. Better detect SHM allocation failures to avoid crash with Bus Error. Fix missing thread unlocks in bootstrap (Fixes #936). Disable network flush by default on H100. Move device code from src/collectives/device to src/device.	2023-09-26 05:50:33 -07:00
Sylvain Jeaugey	55b1d8ab98	Add documentation for NCCL NET plugins ... Also repurpose dummy plugin as example, including headers and compat layers from v6 to v2.	2022-11-22 02:12:53 -08:00