Remove deprecated RMM `Buffer` support #656

vyasr · 2026-05-19T19:43:34Z

We need to update the devcontainers to use CCCL here, then we can change this flag here. That way CCCL support stays optional.

Thanks for pointing that, opened rapidsai/devcontainers#705 to address that.

@pentschev Would it be too much to rename UCXX_ENABLE_RMM to UCXX_ENABLE_RMM_TESTING?
I had the same question as @bdice here

-Original file line number
+Diff line change
@@ Expand Up @@
     ### C++
-    To build and install C++ library to `${CONDA_PREFIX}`, with both Python and RMM support, as well as building all tests and benchmarks (with CUDA support) run:
+    To build and install the C++ library to `${CONDA_PREFIX}`, with Python support and CCCL CUDA buffer support, as well as building all tests and benchmarks with CUDA/CCCL support, run:
     ```
     mkdir cpp/build
@@ Expand All / @@ -53,8 +53,9 @@ cmake .. -DCMAKE_INSTALL_PREFIX=${CONDA_PREFIX} \ @@
           -DBUILD_BENCHMARKS=ON \
           -DCMAKE_BUILD_TYPE=Release \
           -DUCXX_ENABLE_PYTHON=ON \
-          -DUCXX_ENABLE_RMM=ON \
-          -DUCXX_BENCHMARKS_ENABLE_CUDA=ON
+          -DUCXX_ENABLE_CCCL=ON \
+          -DUCXX_BENCHMARKS_ENABLE_CUDA=ON \
+          -DUCXX_BENCHMARKS_ENABLE_CCCL=ON
     make -j install
     ```
@@ Expand Down Expand Up @@
     #### CCCL Memory Support
-    When built with `UCXX_ENABLE_CCCL=ON`, additional CCCL-based memory types are available:
+    When built with `UCXX_ENABLE_CCCL=ON`, `UCXX_BENCHMARKS_ENABLE_CUDA=ON`, and
+    `UCXX_BENCHMARKS_ENABLE_CCCL=ON`, additional CCCL-based memory types are available:
     ```
     # Server with CCCL device memory pool
@@ Expand All @@
     $ ./benchmarks/ucxx_perftest -m cccl-shared -s 1048576 -n 10 127.0.0.1
     ```
-    **Additional CCCL Memory Types (with `-DUCXX_ENABLE_CCCL=ON`):**
+    **Additional CCCL Memory Types:**
     - `cccl-device` - CCCL device memory pool
     - `cccl-shared` - CCCL shared memory resource
     - `cccl-cuda-async` - CCCL CUDA async memory resource
     - `cccl-cuda-async-managed` - CCCL CUDA async managed memory resource
     **Requirements for CCCL Support:**
     - UCXX compiled with `UCXX_ENABLE_CCCL=ON`
+    - Benchmarks compiled with `UCXX_BENCHMARKS_ENABLE_CUDA=ON`
+    - Benchmarks compiled with `UCXX_BENCHMARKS_ENABLE_CCCL=ON`
     - CCCL library available (fetched automatically via CMake)
     ### Python
@@ Expand Down @@

-Original file line number
+Diff line change
@@ Expand Up / @@ -56,7 +56,8 @@ BUILD_TESTS=OFF @@
     BUILD_EXAMPLES=OFF
     BUILD_DISABLE_DEPRECATION_WARNINGS=ON
     BUILD_COMPILE_COMMANDS=OFF
-    UCXX_ENABLE_RMM=OFF
+    UCXX_TESTS_ENABLE_RMM=OFF
+    UCXX_BENCHMARKS_ENABLE_RMM=OFF
     UCXX_ENABLE_CCCL=OFF
     UCXX_BENCHMARKS_ENABLE_CUDA=OFF
@@ Expand Down Expand Up / @@ -151,7 +152,6 @@ if hasArg ucxx_tests && ! hasArg ucxx; then @@
     fi
     if buildAll || hasArg libucxx_python || hasArg libucxx_tests || hasArg libucxx_examples; then
-      UCXX_ENABLE_RMM=ON
       UCXX_ENABLE_CCCL=ON
     fi
@@ Expand Down Expand Up / @@ -188,7 +188,8 @@ if buildAll || hasArg libucxx; then @@
               -DDISABLE_DEPRECATION_WARNINGS=${BUILD_DISABLE_DEPRECATION_WARNINGS} \
               -DCMAKE_BUILD_TYPE=${BUILD_TYPE} \
               -DCMAKE_EXPORT_COMPILE_COMMANDS=${BUILD_COMPILE_COMMANDS} \
-              -DUCXX_ENABLE_RMM=${UCXX_ENABLE_RMM} \
+              -DUCXX_TESTS_ENABLE_RMM=${UCXX_TESTS_ENABLE_RMM} \
+              -DUCXX_BENCHMARKS_ENABLE_RMM=${UCXX_BENCHMARKS_ENABLE_RMM} \
               -DUCXX_ENABLE_CCCL=${UCXX_ENABLE_CCCL} \
               -DUCXX_BENCHMARKS_ENABLE_CUDA=${UCXX_BENCHMARKS_ENABLE_CUDA} \
               "${EXTRA_CMAKE_ARGS[@]}"
@@ Expand Down @@

-Original file line number
+Diff line change
@@ Expand Up / @@ -28,14 +28,12 @@ rapids-pip-retry install \ @@
     # 0 really means "add --no-build-isolation" (ref: https://github.com/pypa/pip/issues/5735)
     export PIP_NO_BUILD_ISOLATION=0
-    export SKBUILD_CMAKE_ARGS="-DUCXX_ENABLE_RMM=ON -DUCXX_ENABLE_CCCL=ON"
+    export SKBUILD_CMAKE_ARGS="-DUCXX_ENABLE_CCCL=ON"
     ./ci/build_wheel.sh "${package_name}" "${package_dir}"
     python -m auditwheel repair \
         --exclude "libucp.so.0" \
-        --exclude "librapids_logger.so" \
-        --exclude "librmm.so" \
         -w "${RAPIDS_WHEEL_BLD_OUTPUT_DIR}" \
         ${package_dir}/dist/*
@@ Expand Down @@

-Original file line number
+Diff line change
@@ Expand Up / @@ -31,8 +31,6 @@ export RAPIDS_PY_API @@
     python -m auditwheel repair \
         --exclude "libucp.so.0" \
         --exclude "libucxx.so" \
-        --exclude "librapids_logger.so" \
-        --exclude "librmm.so" \
         -w "${RAPIDS_WHEEL_BLD_OUTPUT_DIR}" \
         ${package_dir}/dist/*
@@ Expand Down @@

-Original file line number
+Diff line change
@@ Expand Up / @@ -100,19 +100,16 @@ outputs: @@
             - ${{ stdlib("c") }}
           host:
             - cuda-version =${{ cuda_version }}
-            - librmm ${{ rapids_version }}
             - ucx
           run:
             - ${{ pin_compatible("cuda-version", upper_bound="x", lower_bound="x") }}
-            - ${{ pin_compatible("librmm", upper_bound="x.x") }}
             - ucx >=1.18.0,<1.21.0
           run_exports:
             - ${{ pin_subpackage("libucxx", upper_bound="x.x") }}
           ignore_run_exports:
             by_name:
               - cuda-cudart
               - cuda-version
-              - librmm
               - ucx
         tests:
           - script:
@@ Expand Down Expand Up / @@ -173,7 +170,6 @@ outputs: @@
             by_name:
               - cuda-cudart
               - cuda-version
-              - librmm
               - libucxx
               - ucx
         about:
@@ Expand Down @@

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Remove deprecated RMM `Buffer` support #656

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vyasr May 19, 2026

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pentschev May 19, 2026

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nirandaperera May 20, 2026

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-Original file line number
+Diff line change
@@ Expand Up / @@ -93,7 +93,6 @@ outputs: @@
             - python =${{ py_abi_min }}
             - python-abi3 ${{ py_abi_min }}.*
             - rapids-build-backend >=0.4.0,<0.5.0
-            - rmm ${{ rapids_version }}
             - scikit-build-core>=0.11.0
             - ucx
             - libucxx =${{ version }}
@@ Expand All / @@ -106,15 +105,13 @@ outputs: @@
             - python
             - ucx >=1.18.0,<1.21.0
             - ${{ pin_compatible("cuda-version", upper_bound="x", lower_bound="x") }}
-            - ${{ pin_compatible("rmm", upper_bound="x.x") }}
             - libucxx =${{ version }}
           run_constraints:
             - cupy >=13.6.0
           ignore_run_exports:
             by_name:
               - cuda-cudart
               - cuda-version
-              - librmm
               - libucxx
               - python_abi
               - ucx
@@ Expand Down @@

-Original file line number
+Diff line change
@@ Expand Up / @@ -42,7 +42,8 @@ option(BUILD_TESTS "Configure CMake to build tests" ON) @@
     option(BUILD_BENCHMARKS "Configure CMake to build benchmarks" OFF)
     option(BUILD_EXAMPLES "Configure CMake to build examples" OFF)
     option(BUILD_SHARED_LIBS "Build UCXX shared libraries" ON)
-    option(UCXX_ENABLE_RMM "Enable support for CUDA multi-buffer transfer with RMM" OFF)
+    option(UCXX_TESTS_ENABLE_RMM "Enable RMM-backed test code paths" OFF)
+    option(UCXX_BENCHMARKS_ENABLE_RMM "Enable RMM-backed benchmark code paths" OFF)
     # TODO: Flip UCXX_ENABLE_CCCL default to OFF once devcontainer builds pass -DUCXX_ENABLE_CCCL=ON
     option(UCXX_ENABLE_CCCL "Enable support for CUDA buffer with CCCL" ON)
     option(DISABLE_DEPRECATION_WARNINGS "Disable warnings generated from deprecated declarations." OFF)
@@ Expand All @@
     message(VERBOSE "UCXX: Configure CMake to build benchmarks: ${BUILD_BENCHMARKS}")
     message(VERBOSE "UCXX: Configure CMake to build examples: ${BUILD_EXAMPLES}")
     message(VERBOSE "UCXX: Build UCXX shared libraries: ${BUILD_SHARED_LIBS}")
-    message(
-      VERBOSE
-      "UCXX: Enable support for CUDA multi-buffer transfer with RMM (DEPRECATED): ${UCXX_ENABLE_RMM}"
-    )
+    message(VERBOSE "UCXX: Enable RMM-backed test code paths: ${UCXX_TESTS_ENABLE_RMM}")
+    message(VERBOSE "UCXX: Enable RMM-backed benchmark code paths: ${UCXX_BENCHMARKS_ENABLE_RMM}")
     message(VERBOSE "UCXX: Enable support for CUDA buffer with CCCL: ${UCXX_ENABLE_CCCL}")
     message(
       VERBOSE
@@ Expand Down Expand Up / @@ -97,11 +96,13 @@ rapids_find_package( @@
     # add third party dependencies using CPM
     rapids_cpm_init()
-    # find rmm
-    if(UCXX_ENABLE_RMM)
-      message(DEPRECATION "UCXX_ENABLE_RMM is deprecated and will be removed in a future release. "
-                          "Use UCXX_ENABLE_CCCL instead."
-      )
+    # find rmm for enabled test and benchmark code paths
+    if((BUILD_TESTS AND UCXX_TESTS_ENABLE_RMM)
+       OR (BUILD_BENCHMARKS
+           AND UCXX_BENCHMARKS_ENABLE_CUDA
+           AND UCXX_BENCHMARKS_ENABLE_RMM
+          )
+    )
       include(cmake/thirdparty/get_rmm.cmake)
     endif()
     # find cccl
@@ Expand Down Expand Up / @@ -181,13 +182,6 @@ target_include_directories( @@
     target_compile_definitions(ucxx PUBLIC "$<$<COMPILE_LANGUAGE:CXX>:${UCXX_CXX_DEFINITIONS}>")
-    # Enable RMM if necessary
-    if(UCXX_ENABLE_RMM)
-      target_link_libraries(ucxx PUBLIC rmm::rmm)
-      target_compile_definitions(ucxx PUBLIC UCXX_ENABLE_RMM)
-    endif()
     # Enable CCCL if necessary
     if(UCXX_ENABLE_CCCL)
       find_package(CUDAToolkit REQUIRED)
@@ Expand Down @@

-Original file line number
+Diff line change
@@ Expand Up / @@ -45,8 +45,8 @@ function(ConfigureBench CMAKE_BENCH_NAME) @@
         target_link_libraries(${CMAKE_BENCH_NAME} PRIVATE CUDA::cudart_static)
       endif()
-      # RMM memory resources for CUDA benchmarks (requires UCXX_ENABLE_RMM and get_rmm.cmake)
-      if(UCXX_BENCHMARKS_ENABLE_CUDA AND UCXX_ENABLE_RMM)
+      # RMM memory resources for CUDA benchmarks.
+      if(UCXX_BENCHMARKS_ENABLE_CUDA AND UCXX_BENCHMARKS_ENABLE_RMM)
         target_compile_definitions(${CMAKE_BENCH_NAME} PRIVATE UCXX_BENCHMARKS_ENABLE_RMM)
         target_link_libraries(${CMAKE_BENCH_NAME} PRIVATE rmm::rmm)
       endif()
@@ Expand Down @@

-Original file line number
+Diff line change
@@ -1,6 +1,6 @@
     # =================================================================================
     # cmake-format: off
-    # SPDX-FileCopyrightText: Copyright (c) 2023-2025, NVIDIA CORPORATION & AFFILIATES.
+    # SPDX-FileCopyrightText: Copyright (c) 2023-2026, NVIDIA CORPORATION & AFFILIATES.
     # SPDX-License-Identifier: BSD-3-Clause
     # cmake-format: on
     # =================================================================================
@@ Expand Down Expand Up / @@ -31,6 +31,10 @@ function(ConfigureBench CMAKE_BENCH_NAME) @@
                    CXX_STANDARD_REQUIRED ON
       )
       target_link_libraries(${CMAKE_BENCH_NAME} PRIVATE ucxx $<TARGET_NAME_IF_EXISTS:conda_env>)
+      if(UCXX_ENABLE_CCCL)
+        find_package(CUDAToolkit REQUIRED)
+        target_link_libraries(${CMAKE_BENCH_NAME} PRIVATE CUDA::cudart_static)
+      endif()
       add_custom_command(
         OUTPUT UCXX_EXAMPLES
         COMMAND ${CMAKE_BENCH_NAME}
@@ Expand Down @@

-Original file line number
+Diff line change
@@ Expand Up / @@ -18,8 +18,8 @@ @@
     #include <ucxx/utils/sockaddr.h>
     #include <ucxx/utils/ucx.h>
-    #if UCXX_ENABLE_RMM
-    #include <rmm/device_buffer.hpp>
+    #if UCXX_ENABLE_CCCL
+    #include <cuda_runtime_api.h>
     #endif
     class ListenerContext {
@@ Expand Down Expand Up / @@ -91,14 +91,12 @@ static void printUsage() @@
       std::cerr << "              'thread-polling', 'thread-blocking' and 'wait' (default: 'blocking')"
                 << std::endl;
       std::cerr << "  -p <port>   Port number to listen at" << std::endl;
-      std::cerr
-        << "  -s <send_buffer_type>   Send buffer type, valid values are: 'host', 'rmm', 'cccl' "
-           "(default: 'host')"
-        << std::endl;
-      std::cerr
-        << "  -r <recv_buffer_type>   Recv buffer type, valid values are: 'host', 'rmm', 'cccl' "
-           "(default: 'host')"
-        << std::endl;
+      std::cerr << "  -s <send_buffer_type>   Send buffer type, valid values are: 'host', 'cccl' "
+                   "(default: 'host')"
+                << std::endl;
+      std::cerr << "  -r <recv_buffer_type>   Recv buffer type, valid values are: 'host', 'cccl' "
+                   "(default: 'host')"
+                << std::endl;
       std::cerr << "  -h          Print this help" << std::endl;
       std::cerr << std::endl;
     }
@@ Expand All / @@ -124,14 +122,6 @@ struct args { @@
         auto parseBufferType = [](const std::string& bufferTypeString) {
           if (bufferTypeString == "host") {
             return ucxx::BufferType::Host;
-          } else if (bufferTypeString == "rmm") {
-    #if UCXX_ENABLE_RMM
-            return ucxx::BufferType::RMM;
-    #else
-            std::cerr << "RMM support not enabled, please compile with -DUCXX_ENABLE_RMM=1"
-                      << std::endl;
-            return ucxx::BufferType::Invalid;
-    #endif
           } else if (bufferTypeString == "cccl") {
     #if UCXX_ENABLE_CCCL
             return ucxx::BufferType::CCCL;
@@ Expand Down Expand Up @@
       switch (bufferType) {
         case ucxx::BufferType::Host:
           return std::make_shared<ucxx::HostBuffer>(values, size * sizeof(T));
-        case ucxx::BufferType::RMM:
-    #if UCXX_ENABLE_RMM
-        {
-          auto buf =
-            std::make_unique<rmm::device_buffer>(values, size * sizeof(T), rmm::cuda_stream_default);
-          rmm::cuda_stream_default.synchronize();
-          return std::make_shared<ucxx::RMMBuffer>(std::move(buf));
-        }
-    #endif
         case ucxx::BufferType::CCCL:
     #if UCXX_ENABLE_CCCL
         {
@@ Expand All @@
       std::vector<uint8_t> host_expected, host_actual;
       void *host_expected_ptr, *host_actual_ptr;
-    #if UCXX_ENABLE_CCCL || UCXX_ENABLE_RMM
+    #if UCXX_ENABLE_CCCL
       auto copy_to_host = [](auto& buffer, auto& host_buffer) {
         // copy device buffer to host
         host_buffer.resize(buffer->getSize());
@@ Expand All @@
       };
     #endif
-      if (expected->getType() == ucxx::BufferType::RMM ||
-          expected->getType() == ucxx::BufferType::CCCL) {
+      if (expected->getType() == ucxx::BufferType::CCCL) {
         host_expected_ptr = copy_to_host(expected, host_expected);
       } else {
         host_expected_ptr = expected->data();
       }
-      if (actual->getType() == ucxx::BufferType::RMM || actual->getType() == ucxx::BufferType::CCCL) {
+      if (actual->getType() == ucxx::BufferType::CCCL) {
         host_actual_ptr = copy_to_host(actual, host_actual);
       } else {
         host_actual_ptr = actual->data();
@@ Expand Down @@

-Original file line number
+Diff line change
@@ -1,13 +1,9 @@
     /**
-     * SPDX-FileCopyrightText: Copyright (c) 2022-2025, NVIDIA CORPORATION & AFFILIATES.
+     * SPDX-FileCopyrightText: Copyright (c) 2022-2026, NVIDIA CORPORATION & AFFILIATES.
      * SPDX-License-Identifier: BSD-3-Clause
      */
     #pragma once
-    #ifndef UCXX_ENABLE_RMM
-    #define UCXX_ENABLE_RMM 0
-    #endif
     #include <ucxx/address.h>
     #include <ucxx/buffer.h>
     #include <ucxx/constructors.h>
@@ Expand Down @@

Remove deprecated RMM Buffer support #656

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vyasr May 19, 2026

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pentschev May 19, 2026

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nirandaperera May 20, 2026

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Remove deprecated RMM `Buffer` support #656

Remove deprecated RMM `Buffer` support #656