Enabling OFI/verbs dmabuf support

oneCCL provides experimental support for device memory transfers using Linux dmabuf, which is exposed through OFI API for verbs provider.


  • Linux kernel version >= 5.12

  • RDMA core version >= 34.0

  • level-zero-devel package


  • Only first tile should be used from each GPU card. For example, if GPU with 2 tiles is used then set ZE_AFFINITY_MASK=0.0. More information about GPU selection can be found in level-zero documentation.

Build instructions


git clone --single-branch --branch v1.13.1 https://github.com/ofiwg/libfabric.git
cd libfabric
./configure --prefix=<ofi_install_dir> --enable-verbs=<rdma_core_install_dir> --enable-ze-dlopen=yes
make -j install


You may also get OFI release package directly from here. No need to run autogen.sh if using the release package.


cmake -DCMAKE_INSTALL_PREFIX=<ccl_install_dir> -DLIBFABRIC_DIR=<ofi_install_dir> -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=dpcpp -DCOMPUTE_BACKEND=dpcpp_level_zero -DENABLE_OFI_HMEM=1 ..
make -j install

Run instructions

Run allreduce test with ring algorithm and SYCL USM device buffers.

source <ccl_install_dir>/env/setvars.sh
export LD_LIBRARY_PATH=<ofi_install_path>/lib:${LD_LIBRARY_PATH}
CCL_ATL_TRANSPORT=ofi CCL_ATL_HMEM=1 CCL_ALLREDUCE=ring FI_PROVIDER=verbs mpiexec -n 2 <ccl_install_dir>/examples/sycl/sycl_allreduce_usm_test gpu device