SRC/PLUGINS/UCX_MO: Removed Multi-Object UCX backend. (#898)

Signed-off-by: Raul Akhmetshin <[email protected]>

Author: rakhmets

.gitlab/test_cpp.sh

@@ -68,10 +68,6 @@ if $TEST_LIBFABRIC ; then
 fi
 ./bin/nixl_etcd_example
 ./bin/ucx_backend_test
-# Skip UCX_MO backend test on GPU worker, fails VRAM transfers
-if ! $HAS_GPU ; then
-    ./bin/ucx_mo_backend_test
-fi
 mkdir -p /tmp/telemetry_test
 NIXL_TELEMETRY_ENABLE=y NIXL_TELEMETRY_DIR=/tmp/telemetry_test ./bin/agent_example &
 sleep 1

benchmark/kvbench/README.md

@@ -118,7 +118,7 @@ These arguments are used by both `plan` and `profile` commands:
 | -------- | ----------- |
 | `--source` | Source of the nixl descriptors [file, memory, gpu] (default: file) |
 | `--destination` | Destination of the nixl descriptors [file, memory, gpu] (default: memory) |
-| `--backend` | Communication backend [UCX, UCX_MO, GDS, GDS_MT, POSIX, GPUNETIO, Mooncake, HF3FS, OBJ] (default: UCX) |
+| `--backend` | Communication backend [UCX, GDS, GDS_MT, POSIX, GPUNETIO, Mooncake, HF3FS, OBJ] (default: UCX) |
 | `--worker_type` | Worker to use to transfer data [nixl, nvshmem] (default: nixl) |
 | `--initiator_seg_type` | Memory segment type for initiator [DRAM, VRAM] (default: DRAM) |
 | `--target_seg_type` | Memory segment type for target [DRAM, VRAM] (default: DRAM) |

benchmark/kvbench/commands/args.py

@@ -72,7 +72,7 @@ def nixl_bench_args(func):
     func = click.option(
         "--backend",
         type=str,
-        help="Communication backend [UCX, UCX_MO, GDS, GDS_MT, POSIX, GPUNETIO, Mooncake, HF3FS, OBJ] (default: UCX)",
+        help="Communication backend [UCX, GDS, GDS_MT, POSIX, GPUNETIO, Mooncake, HF3FS, OBJ] (default: UCX)",
     )(func)
     func = click.option(
         "--worker_type",

benchmark/kvbench/commands/nixlbench.py

@@ -205,7 +205,7 @@ def _configure_posix(self, source: str, destination: str):
             raise ValueError(f"Invalid source for POSIX/HF3FS: {source}")
 
     def _configure_ucx(self, backend: str, source: str, destination: str):
-        """Configure UCX, UCX_MO, GPUNETIO, and Mooncake plugins (same logic for all)"""
+        """Configure UCX, GPUNETIO, and Mooncake plugins (same logic for all)"""
         arg_to_seg_type = {
             "memory": "DRAM",
             "gpu": "VRAM",
@@ -241,7 +241,7 @@ def configure_segment_type(self, backend: str, source: str, destination: str):
             self._configure_gds(source, destination)
         elif backend_lower in ["posix", "hf3fs"]:
             self._configure_posix(source, destination)
-        elif backend_lower in ["ucx", "ucx_mo", "gpunetio", "mooncake"]:
+        elif backend_lower in ["ucx", "gpunetio", "mooncake"]:
             self._configure_ucx(backend_lower, source, destination)
         elif backend_lower == "obj":
             self._configure_obj(source, destination)

benchmark/nixlbench/README.md

@@ -32,7 +32,7 @@ A comprehensive benchmarking tool for the NVIDIA Inference Xfer Library (NIXL) t
 
 ## Features
 
-- **Multiple Communication Backends**: UCX, UCX_MO, GPUNETIO, Mooncake, Libfabric for network communication
+- **Multiple Communication Backends**: UCX, GPUNETIO, Mooncake, Libfabric for network communication
 - **Storage Backend Support**: GDS, GDS_MT, POSIX, HF3FS, OBJ (S3), GUSLI for storage operations
 - **Flexible Communication Patterns**:
   - **Pairwise**: Point-to-point communication between pairs
@@ -420,7 +420,7 @@ sudo systemctl start etcd && sudo systemctl enable etcd
 ```
 --runtime_type NAME        # Type of runtime to use [ETCD] (default: ETCD)
 --worker_type NAME         # Worker to use to transfer data [nixl, nvshmem] (default: nixl)
---backend NAME             # Communication backend [UCX, UCX_MO, GDS, GDS_MT, POSIX, GPUNETIO, Mooncake, HF3FS, OBJ, GUSLI] (default: UCX)
+--backend NAME             # Communication backend [UCX, GDS, GDS_MT, POSIX, GPUNETIO, Mooncake, HF3FS, OBJ, GUSLI] (default: UCX)
 --benchmark_group NAME     # Name of benchmark group for parallel runs (default: default)
 --etcd_endpoints URL       # ETCD server URL for coordination (default: http://localhost:2379)
 ```
@@ -520,7 +520,7 @@ Note: storage_enable_direct is automatically enabled for GUSLI backend
 NIXL Benchmark uses an ETCD key-value store for coordination between benchmark workers. This is useful in containerized or cloud-native environments.
 
 **ETCD Requirements:**
-- **Required**: Network backends (UCX, UCX_MO, GPUNETIO, Mooncake, Libfabric) and multi-node setups
+- **Required**: Network backends (UCX, GPUNETIO, Mooncake, Libfabric) and multi-node setups
 - **Optional**: Storage backends (GDS, GDS_MT, POSIX, HF3FS, OBJ, GUSLI) running as single instances
 - **Required**: Storage backends when `--etcd_endpoints` is explicitly specified
 
@@ -565,9 +565,6 @@ The workers automatically coordinate ranks through ETCD as they connect.
 
 # UCX with specific devices
 ./nixlbench --etcd_endpoints http://etcd-server:2379 --backend UCX --device_list mlx5_0,mlx5_1
-
-# UCX Memory-Only variant
-./nixlbench --etcd_endpoints http://etcd-server:2379 --backend UCX_MO
 ```
 
 **GPUNETIO Backend:**

benchmark/nixlbench/src/utils/utils.cpp

@@ -47,7 +47,7 @@ DEFINE_string(worker_type, XFERBENCH_WORKER_NIXL, "Type of worker [nixl, nvshmem
 DEFINE_string(
     backend,
     XFERBENCH_BACKEND_UCX,
-    "Name of NIXL backend [UCX, UCX_MO, GDS, GDS_MT, POSIX, GPUNETIO, Mooncake, HF3FS, OBJ, GUSLI] \
+    "Name of NIXL backend [UCX, GDS, GDS_MT, POSIX, GPUNETIO, Mooncake, HF3FS, OBJ, GUSLI] \
               (only used with nixl worker)");
 DEFINE_string(initiator_seg_type, XFERBENCH_SEG_TYPE_DRAM, "Type of memory segment for initiator \
               [DRAM, VRAM]. Note: Storage backends always use DRAM locally.");
@@ -431,8 +431,7 @@ xferBenchConfig::printConfig() {
     }
     printOption("Worker type (--worker_type=[nixl,nvshmem])", worker_type);
     if (worker_type == XFERBENCH_WORKER_NIXL) {
-        printOption("Backend (--backend=[UCX,UCX_MO,GDS,GDS_MT,POSIX,Mooncake,HF3FS,OBJ])",
-                    backend);
+        printOption("Backend (--backend=[UCX,GDS,GDS_MT,POSIX,Mooncake,HF3FS,OBJ])", backend);
         printOption ("Enable pt (--enable_pt=[0,1])", std::to_string (enable_pt));
         printOption("Progress threads (--progress_threads=N)", std::to_string(progress_threads));
         printOption ("Device list (--device_list=dev1,dev2,...)", device_list);

benchmark/nixlbench/src/utils/utils.h

@@ -66,7 +66,6 @@
 
 // Backend types
 #define XFERBENCH_BACKEND_UCX "UCX"
-#define XFERBENCH_BACKEND_UCX_MO "UCX_MO"
 #define XFERBENCH_BACKEND_LIBFABRIC "LIBFABRIC"
 #define XFERBENCH_BACKEND_GDS "GDS"
 #define XFERBENCH_BACKEND_GDS_MT "GDS_MT"

benchmark/nixlbench/src/worker/nixl/nixl_worker.cpp

@@ -113,7 +113,6 @@ xferBenchNixlWorker::xferBenchNixlWorker(int *argc, char ***argv, std::vector<st
     agent->getAvailPlugins(plugins);
 
     if (0 == xferBenchConfig::backend.compare(XFERBENCH_BACKEND_UCX) ||
-        0 == xferBenchConfig::backend.compare(XFERBENCH_BACKEND_UCX_MO) ||
         0 == xferBenchConfig::backend.compare(XFERBENCH_BACKEND_LIBFABRIC) ||
         0 == xferBenchConfig::backend.compare(XFERBENCH_BACKEND_GPUNETIO) ||
         0 == xferBenchConfig::backend.compare(XFERBENCH_BACKEND_MOONCAKE) ||
@@ -126,23 +125,16 @@ xferBenchNixlWorker::xferBenchNixlWorker(int *argc, char ***argv, std::vector<st
 
     agent->getPluginParams(backend_name, mems, backend_params);
 
-    if (0 == xferBenchConfig::backend.compare(XFERBENCH_BACKEND_UCX) ||
-        0 == xferBenchConfig::backend.compare(XFERBENCH_BACKEND_UCX_MO)) {
+    if (0 == xferBenchConfig::backend.compare(XFERBENCH_BACKEND_UCX)) {
         backend_params["num_threads"] = std::to_string(xferBenchConfig::progress_threads);
 
         // No need to set device_list if all is specified
         // fallback to backend preference
         if (devices[0] != "all" && devices.size() >= 1) {
             if (isInitiator()) {
                 backend_params["device_list"] = devices[rank];
-                if (0 == xferBenchConfig::backend.compare(XFERBENCH_BACKEND_UCX_MO)) {
-                    backend_params["num_ucx_engines"] = xferBenchConfig::num_initiator_dev;
-                }
             } else {
                 backend_params["device_list"] = devices[rank - xferBenchConfig::num_initiator_dev];
-                if (0 == xferBenchConfig::backend.compare(XFERBENCH_BACKEND_UCX_MO)) {
-                    backend_params["num_ucx_engines"] = xferBenchConfig::num_target_dev;
-                }
             }
         }
 

src/core/meson.build

@@ -29,10 +29,6 @@ if 'UCX' in static_plugins
     nixl_lib_deps += [ ucx_backend_interface, asio_dep, cuda_dep ]
 endif
 
-if 'UCX_MO' in static_plugins
-    nixl_lib_deps += [ ucx_mo_backend_interface, cuda_dep ]
-endif
-
 if 'POSIX' in static_plugins
     nixl_lib_deps += [ posix_backend_interface ]
 endif

src/core/nixl_plugin_manager.cpp

@@ -403,10 +403,6 @@ void nixlPluginManager::registerBuiltinPlugins() {
     NIXL_REGISTER_STATIC_PLUGIN(UCX)
 #endif
 
-#ifdef STATIC_PLUGIN_UCX_MO
-    NIXL_REGISTER_STATIC_PLUGIN(UCX_MO)
-#endif
-
 #ifdef STATIC_PLUGIN_GDS
 #ifndef DISABLE_GDS_BACKEND
     NIXL_REGISTER_STATIC_PLUGIN(GDS)