Introduction of the raft::device_resources_snmg type

cpp/include/raft/core/device_resources_snmg.hpp

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+/*
+ * Copyright (c) 2024, NVIDIA CORPORATION.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <raft/core/device_resources.hpp>
+
+#include <nccl.h>
+#include <omp.h>
+
+#include <memory>
+#include <vector>
+
+/**
+ * @brief Error checking macro for NCCL runtime API functions.
+ *
+ * Invokes a NCCL runtime API function call, if the call does not return ncclSuccess, throws an
+ * exception detailing the NCCL error that occurred
+ */
+#define RAFT_NCCL_TRY(call)                        \
+  do {                                             \
+    ncclResult_t const status = (call);            \
+    if (ncclSuccess != status) {                   \
+      std::string msg{};                           \
+      SET_ERROR_MSG(msg,                           \
+                    "NCCL error encountered at: ", \
+                    "call='%s', Reason=%d:%s",     \
+                    #call,                         \
+                    status,                        \
+                    ncclGetErrorString(status));   \
+      throw raft::logic_error(msg);                \
+    }                                              \
+  } while (0);
+
+namespace raft {
+
+class device_resources_snmg : public resources {
+ public:
+  device_resources_snmg() : resources{}, root_rank_(0)
+  {
+    int num_ranks;
+    RAFT_CUDA_TRY(cudaGetDeviceCount(&num_ranks));
+    device_ids_.resize(num_ranks);
+    std::iota(device_ids_.begin(), device_ids_.end(), 0);
+    nccl_comms_.resize(num_ranks);
+    initialize();
+  }
+
+  device_resources_snmg(const std::vector<int>& device_ids)
+    : resources{}, root_rank_(0), device_ids_(device_ids), nccl_comms_(device_ids.size())
+  {
+    initialize();
+  }
+
+  device_resources_snmg(const device_resources_snmg& clique)
+    : resources(clique),
+      root_rank_(clique.root_rank_),
+      device_ids_(clique.device_ids_),
+      nccl_comms_(clique.nccl_comms_),
+      device_resources_(clique.device_resources_)
+  {
+  }
+
+  device_resources_snmg(device_resources_snmg&&)            = delete;
+  device_resources_snmg& operator=(device_resources_snmg&&) = delete;
+
+  inline int set_root_rank(int rank) { this->root_rank_ = rank; }
+
+  inline int get_root_rank() const { return this->root_rank_; }
+
+  inline int get_num_ranks() const { return this->device_ids_.size(); }
+
+  inline int get_device_id(int rank) const { return this->device_ids_[rank]; }
+
+  inline ncclComm_t get_nccl_comm(int rank) const { return this->nccl_comms_[rank]; }
+
+  inline const raft::device_resources& get_device_resources(int rank) const
+  {
+    return this->device_resources_[rank];
+  }
+
+  inline const raft::device_resources& set_current_device_to_root_rank() const
+  {
+    int root_device_id = get_device_id(get_root_rank());
+    RAFT_CUDA_TRY(cudaSetDevice(root_device_id));
+    return get_device_resources(root_rank_);
+  }
+
+  inline const raft::device_resources& set_current_device_to_rank(int rank) const
+  {
+    RAFT_CUDA_TRY(cudaSetDevice(get_device_id(rank)));
+    return get_device_resources(rank);
+  }
+
+  void set_memory_pool(int percent_of_free_memory) const
+  {
+    for (int rank = 0; rank < get_num_ranks(); rank++) {
+      RAFT_CUDA_TRY(cudaSetDevice(get_device_id(rank)));
+      size_t limit =
+        rmm::percent_of_free_device_memory(percent_of_free_memory);  // check limit for each device
+      raft::resource::set_workspace_to_pool_resource(get_device_resources(rank), limit);
+    }
+  }
+
+  ~device_resources_snmg()
+  {
+#pragma omp parallel for  // necessary to avoid hangs
+    for (int rank = 0; rank < get_num_ranks(); rank++) {
+      RAFT_CUDA_TRY(cudaSetDevice(get_device_id(rank)));
+      RAFT_NCCL_TRY(ncclCommDestroy(get_nccl_comm(rank)));
+    }
+  }
+
+ private:
+  void initialize()
+  {
+    RAFT_NCCL_TRY(ncclCommInitAll(nccl_comms_.data(), get_num_ranks(), device_ids_.data()));
+
+    for (int rank = 0; rank < get_num_ranks(); rank++) {
+      RAFT_CUDA_TRY(cudaSetDevice(get_device_id(rank)));
+      device_resources_.emplace_back();
+
+      // ideally add the ncclComm_t to the device_resources object with
+      // raft::comms::build_comms_nccl_only
+    }
+  }
+
+  int root_rank_;
+  std::vector<int> device_ids_;
+  std::vector<ncclComm_t> nccl_comms_;
+  std::vector<raft::device_resources> device_resources_;
+
+};  // class device_resources_snmg
+
+}  // namespace raft