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/home/docs/checkouts/readthedocs.org/user_builds/advanced-micro-devices-hipcub/checkouts/docs-5.7.1/hipcub/include/hipcub/backend/rocprim/grid/grid_barrier.hpp Source File#

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 /******************************************************************************
  * Copyright (c) 2011, Duane Merrill.  All rights reserved.
  * Copyright (c) 2011-2018, NVIDIA CORPORATION.  All rights reserved.
  * Modifications Copyright (c) 2021, Advanced Micro Devices, Inc.  All rights reserved.
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 #ifndef HIPCUB_ROCPRIM_GRID_GRID_BARRIER_HPP_
 #define HIPCUB_ROCPRIM_GRID_GRID_BARRIER_HPP_
  
 #include <type_traits>
  
 #include "../../../config.hpp"
  
 #include "../../../thread/thread_load.hpp"
  
 BEGIN_HIPCUB_NAMESPACE
  
 class GridBarrier
 {
 protected :
  
     typedef unsigned int SyncFlag;
  
     // Counters in global device memory
     SyncFlag* d_sync;
  
 public:
  
     GridBarrier() : d_sync(NULL) {}
  
     __device__ __forceinline__ void Sync() const
     {
         volatile SyncFlag *d_vol_sync = d_sync;
  
         // Threadfence and syncthreads to make sure global writes are visible before
         // thread-0 reports in with its sync counter
         __threadfence();
         __syncthreads();
  
         if (blockIdx.x == 0)
         {
             // Report in ourselves
             if (threadIdx.x == 0)
             {
                 d_vol_sync[blockIdx.x] = 1;
             }
  
             __syncthreads();
  
             // Wait for everyone else to report in
             for (uint32_t peer_block = threadIdx.x; peer_block < gridDim.x; peer_block += blockDim.x)
             {
                 while (ThreadLoad<LOAD_CG>(d_sync + peer_block) == 0)
                 {
                     __threadfence_block();
                 }
             }
  
             __syncthreads();
  
             // Let everyone know it's safe to proceed
             for (uint32_t peer_block = threadIdx.x; peer_block < gridDim.x; peer_block += blockDim.x)
             {
                 d_vol_sync[peer_block] = 0;
             }
         }
         else
         {
             if (threadIdx.x == 0)
             {
                 // Report in
                 d_vol_sync[blockIdx.x] = 1;
  
                 // Wait for acknowledgment
                 while (ThreadLoad<LOAD_CG>(d_sync + blockIdx.x) == 1)
                 {
                     __threadfence_block();
                 }
             }
  
             __syncthreads();
         }
     }
 };
  
  
 class GridBarrierLifetime : public GridBarrier
 {
 protected:
  
     // Number of bytes backed by d_sync
     size_t sync_bytes;
  
 public:
  
     GridBarrierLifetime() : GridBarrier(), sync_bytes(0) {}
  
  
     hipError_t HostReset()
     {
         hipError_t retval = hipSuccess;
         if (d_sync)
         {
             retval = hipFree(d_sync);
             d_sync = NULL;
         }
         sync_bytes = 0;
         return retval;
     }
  
  
     virtual ~GridBarrierLifetime()
     {
         HostReset();
     }
  
  
     hipError_t Setup(int sweep_grid_size)
     {
         hipError_t retval = hipSuccess;
         do {
             size_t new_sync_bytes = sweep_grid_size * sizeof(SyncFlag);
             if (new_sync_bytes > sync_bytes)
             {
                 if (d_sync)
                 {
                     if ((retval = hipFree(d_sync))) break;
                 }
  
                 sync_bytes = new_sync_bytes;
  
                 // Allocate and initialize to zero
                 if ((retval = hipMalloc((void**) &d_sync, sync_bytes))) break;
                 if ((retval = hipMemset(d_sync, 0, new_sync_bytes))) break;
             }
         } while (0);
  
         return retval;
     }
 };
  
 END_HIPCUB_NAMESPACE
  
 #endif // HIPCUB_ROCPRIM_GRID_GRID_BARRIER_HPP_