first cut on collectives and sync

code is based on the GPUIB implementations of the routines, which seem
however generic enough to work also for the IPC conduit.

Some code is in for broadcast, fcollect, and alltoall.

src/ipc/context_ipc_device_coll.cpp

@@ -0,0 +1,120 @@
+/******************************************************************************
+ * Copyright (c) 2024 Advanced Micro Devices, Inc. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *****************************************************************************/
+
+#include "roc_shmem/roc_shmem.hpp"
+#include "../context_incl.hpp"
+#include "context_ipc_tmpl_device.hpp"
+#include "../util.hpp"
+#include "ipc_team.hpp"
+
+namespace rocshmem {
+
+__device__ void IPCContext::internal_direct_barrier(int pe, int PE_start,
+                                                      int stride, int n_pes,
+                                                      int64_t *pSync) {
+  int64_t flag_val = 1;
+  if (pe == PE_start) {
+    // Go through all PE offsets (except current offset = 0)
+    // and wait until they all reach
+    for (size_t i = 1; i < n_pes; i++) {
+      wait_until(&pSync[i], ROC_SHMEM_CMP_EQ, flag_val);
+      pSync[i] = ROC_SHMEM_SYNC_VALUE;
+    }
+    threadfence_system();
+
+    // Announce to other PEs that all have reached
+    for (size_t i = 1, j = PE_start + stride; i < n_pes; ++i, j += stride) {
+      put_nbi(&pSync[0], &flag_val, 1, j);
+    }
+  } else {
+    // Mark current PE offset as reached
+    size_t pe_offset = (pe - PE_start) / stride;
+    put_nbi(&pSync[pe_offset], &flag_val, 1, PE_start);
+    wait_until(&pSync[0], ROC_SHMEM_CMP_EQ, flag_val);
+    pSync[0] = ROC_SHMEM_SYNC_VALUE;
+    threadfence_system();
+  }
+}
+
+__device__ void IPCContext::internal_atomic_barrier(int pe, int PE_start,
+                                                      int stride, int n_pes,
+                                                      int64_t *pSync) {
+  int64_t flag_val = 1;
+  if (pe == PE_start) {
+    wait_until(&pSync[0], ROC_SHMEM_CMP_EQ, (int64_t)(n_pes - 1));
+    pSync[0] = ROC_SHMEM_SYNC_VALUE;
+    threadfence_system();
+
+    for (size_t i = 1, j = PE_start + stride; i < n_pes; ++i, j += stride) {
+      put_nbi(&pSync[0], &flag_val, 1, j);
+    }
+  } else {
+    amo_add<int64_t>(&pSync[0], flag_val, PE_start);
+    wait_until(&pSync[0], ROC_SHMEM_CMP_EQ, flag_val);
+    pSync[0] = ROC_SHMEM_SYNC_VALUE;
+    threadfence_system();
+  }
+}
+
+// Uses PE values that are relative to world
+__device__ void IPCContext::internal_sync(int pe, int PE_start, int stride,
+                                          int PE_size, int64_t *pSync) {
+  __syncthreads();
+  if (is_thread_zero_in_block()) {
+    if (PE_size < 64) {
+      internal_direct_barrier(pe, PE_start, stride, PE_size, pSync);
+    } else {
+      internal_atomic_barrier(pe, PE_start, stride, PE_size, pSync);
+    }
+  }
+  __threadfence();
+  __syncthreads();
+}
+
+__device__ void IPCContext::sync(roc_shmem_team_t team) {
+  IPCTeam *team_obj = reinterpret_cast<IPCTeam *>(team);
+
+  /**
+   * Ensure that the stride is a multiple of 2.
+   */
+  int log_pe_stride = static_cast<int>(team_obj->tinfo_wrt_world->log_stride);
+  int pe = team_obj->my_pe_in_world;
+  int pe_start = team_obj->tinfo_wrt_world->pe_start;
+  int pe_stride = (1 << log_pe_stride);
+  int pe_size = team_obj->num_pes;
+
+  internal_sync(pe, pe_start, pe_stride, pe_size, barrier_sync);
+}
+
+__device__ void IPCContext::sync_all() {
+  internal_sync(my_pe, 0, 1, num_pes, barrier_sync);
+}
+
+__device__ void IPCContext::barrier_all() {
+  if (is_thread_zero_in_block()) {
+    quiet();
+  }
+  sync_all();
+  __syncthreads();
+}
+
+}  // namespace rocshmem