2 次代码提交

作者	SHA1	备注	提交日期
Kamil Iskra	72d2432094	NCCL 2.27.3-1 ... Symmetric memory API and symmetric kernels * Redesign from the ground up, enabling major latency and bandwidth improvements. * Add new API calls to register user-allocated memory among communicator ranks into a NCCL window: ncclCommWindowRegister() and ncclCommWindowDeregister(). The calls currently support symmetric registration for P2P and NVLS, and require VMM memory buffers (i.e., CUMEM must be operational). * Implement specialized kernels taking advantage of symmetrically registered memory, with performance gains expected particularly for small to medium message sizes. * The kernels support 32 bit floating point types and smaller, and sum as the reduction operator, with no more than one collective operation per group. * Floating point summation is always done in fp32 accumulators (with the exception of fp8 on NVLS, where it uses fp16 inside the switch). Thus, the accuracy with fp8 and fp16 data types should be much improved. * This initial implementation supports non-network communicators only (P2P and NVLS transports). * To explore this functionality users need to use the new memory registration API calls with the NCCL_WIN_COLL_SYMMETRIC flag and all ranks of a communicator must pass buffers at the same offset in the same registration when invoking a collective NCCL operation. Add support for DGX Spark. Add support for DirectNIC (CX8) to the internal IB plugin. Add a new ncclCommShrink() API call * It is a non-collective call similar to ncclCommSplit(), which makes it possible to exclude some (possibly unresponsive) ranks from the parent communicator. Add support for loading multiple network plugins * This enables the creation of generic containers that can work across a range of providers. * Allow NCCL_NET_PLUGIN to accept a comma-separated list of plugins to load. NVLink SHARP (NVLS) improvements * Implement NVLS+IB SHARP support for AllGather and ReduceScatter with user buffer registration. This improves performance and reduces the number of CTAs needed to achieve peak bandwidth. * Gracefully fall back by default to other transports if NVLS initialization fails (the old behavior of returning an error code from a NCCL call can be preserved by setting NCCL_NVLS_ENABLE=1). * Decrease the NVLS channel count to 24 on Blackwell systems with multiple NVLink domains per communicator. * Enable fine-tuning of NCCL behavior per communicator using new "ncclConfig_t" members "collnetEnable", "CTAPolicy", and "nvlsCTAs". Profiler improvements * Extend the init function by adding communicator name, comm id (hash), rank, number of ranks, number of nodes, and the NCCL log function to the argument list. This makes the name and the comm id available to all events in the communicator without explicitly passing them to each individual event. Add the communicator id and rank to the profiler trace filename. Now, the communicator name can be set via a new "ncclConfig_t" member "commName". * Improve the accuracy of the GPU kernel events by providing GPU-generated timestamps for the start and stop of every NCCL operation. * Harmonize proxy events, removing overlaps between ProxyOp and ProxyStep states. * Add support for network-defined event updates (through "recordEventState"). * Report the correct number of channels used by every collective/p2p operation (used to be set to nMaxChannels for collectives and absent for p2ps). * Fix the logic on proxyCtrl Idle/Active events (Issue #1162). * Fix an issue where the network proxy profiler could lose track of an event identifier (Issue #1682). * Improve the backward compatibility with plugins older than v4. * Ensure that the work counters are 0-initialized. * Fix a potential race condition in the network profiler that could result in an event being linked to a wrong parent. MNNVL improvements * Increase to 16 the number of NICs used to communicate between MNNVL domains on GB200 systems, to optimize the performance of collective operations. * Add support for more complex MNNVL topologies with up to 32 NICs per node. * If the MNNVL fabric initialization was unsuccessful, NCCL will now fail by default, so as to avoid inadvertently falling back to a potentially much slower network transport. Such failures are typically due to a misconfigured IMEX support on the system. To continue without MNNVL, restart the job with NCCL_MNNVL_ENABLE=0. * Fix a potential hang in alltoall-like communication patterns at a scale of over 80 ranks. * Make NCCL_P2P_DISABLE=1 imply NCCL_MNNVL_ENABLE=0 (so the latter no longer needs to be specified on MNNVL systems). * Fix an initialization failure when NCCL_TOPO_FILE is used on MNNVL systems. * Fix the graph search to exclude non-local NICs. * Fix the SHM transport to use fabric handles on MNNVL systems. NIC Fusion improvements * Disable the creation of fused NICs for physical devices that haven't been merged. * Flatten multiple ports to a single PCI device within the internal IB plugin and reparent dual-port NICs under the first PCI parent. If the parent is not a PCI switch, PCI devices for fused NICs won't be duplicated. * Route traffic on GB200-CX8 systems through DirectNIC, not the host interface. Improve support for platforms with C2C connectivity (e.g., GB200) * Enable GPUDirect RDMA for the NICs by default. * Add support for P2C (PXN over C2C) and the LL128 protocol. Extend NCCL fault tolerance in multithreaded scenarios * Support the creation of multiple nonblocking communicators within a single group and polling in parallel for the completion using multiple threads (one per communicator). Enable ncclImplicitOrderLaunch for CUDA 12.9+ * This can potentially speed up NCCL_IMPLICIT_LAUNCH_ORDER. Improve the netSocket transport latency and control * Provide finer control over the size of the socket send/receive buffers, the task size, and the number of sockets that a single peer can open. * Add support for the inlining of small messages behind the header when using multiple sockets per connection. Improve the readability of the CPU affinity in the debug output * Print it as a range string rather than a bitmask. Fix a potential race condition in graph execution * A contention could arise when mixing graph and non-graph execution. Improve PXN connection code * Avoid duplicate and unused connections. RAS fixes * Fix a memory corruption at job termination time in case of a previously failed initialization of a RAS socket connection. * Fix a race condition leading to a crash when generating a RAS report during communicator initialization (Issues #1669, #1718). * Fix a potential race condition when gathering data for a RAS status report. Fix a potential memory corruption in ncclCommSplit() * Memory could get corrupted when resource sharing was in use and the size of the NVLink domain in the new communicator was smaller than in the old one. Fix asynchronous graph upload * Fix a small memory leak. * Fix oversychronization. Add a check for out-of-memory conditions in ncclMemAlloc() Clean up the NCCL socket code * accept() will retry also if just reading the magic failed (Issue #1613). * connect() will retry also if poll() did not return a POLLOUT event (Issue #1618). * Add error checking in a few instances (Issue #1539). * Fix the loop condition in ncclFindInterfaceMatchSubnet() (Issue #1574). * Clean up the debug output, downgrading WARN messages to INFO in non-critical cases, and printing the peer's address where relevant. Switch NCCL_DEBUG_FILE to line buffering * This should help avoid mixed-up partial output lines in multithreaded cases. Other minor fixes * Improve the checks for buffer overflows in the graph code (Issue #1585). * Extend logging and state clearing to all four events in the internal IB plugin (Issue #1650). * Fix the error path in case IB communication is not ready (Issue #1489). * Add ECE logging for IB fabric. * Fix various minor issues in the graph module (Issue #1635). * Clean up the debug output in the graph code, downgrading WARN messages to INFO in non-critical cases. * Add a missing argument to a directSend() call (Issue #1628). * Remove duplicate code in sendProxySetup() (Issue #1420). * Fix the order of arguments of cudaDeviceCanAccessPeer() (Issue #1507). * Fix compiler warnings with GCC 14. * Fix a typo in a comment (Issue #1236).	2025-05-29 20:56:40 -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