/*************************************************************************
 * Copyright (c) 2016-2022, NVIDIA CORPORATION. All rights reserved.
 * Modifications Copyright (c) 2019-2023 Advanced Micro Devices, Inc. All rights reserved.
 *
 * See LICENSE.txt for license information
 ************************************************************************/

#include "comm.h"
#include "graph.h"
#include "utils.h"
#include "shm.h"
#include "graph.h"
#include "graph/topo.h"

struct ncclP2pBuff {
  void* directPtr;
  cudaIpcMemHandle_t devIpc;
};

struct p2pConnectInfo {
  int rank;
  int read;
  struct ncclP2pBuff p2pBuff;
  // Use by CE memcpy
  char shmName[7];
  int shmSize;
};
static_assert(sizeof(struct p2pConnectInfo) <= CONNECT_SIZE, "p2pConnectInfo is too large");

struct p2pShm {
  struct ncclSendMem sendMem;
  struct ncclRecvMem recvMem;
};
struct p2pProxyInfo {
  // Shared memory between proxy and receiving GPU
  struct p2pShm* shm;
  struct p2pShm* devShm;
  char shmName[7];
  int shmSize;
  ncclShmHandle_t handle;

  // Intermediate step for sender
  struct ncclRecvMem* ceRecvMem;
  char* ceDevBuff;

  // Receiver buffer
  char* recvFifo;

  // Used by progress only
  uint64_t step;
  cudaStream_t stream;
  cudaEvent_t events[NCCL_STEPS];
};
static_assert(sizeof(p2pConnectInfo) <= CONNECT_SIZE, "P2P Connect info is too large");

struct p2pSendResources {
  struct ncclSendMem* devMem;
  uint32_t* next_hdp_reg;  // Next GPU in ring (for p2p transport use only)
  void* sendMemIpc;
  void* recvMemIpc;
  struct p2pProxyInfo proxyInfo;
};

struct p2pRecvResources {
  struct ncclRecvMem* devMem;
  void* sendMemIpc;
  void* recvMemIpc;
  struct p2pShm* shm;
  struct p2pShm* devShm;
  int shmSize;
  ncclShmHandle_t handle;
};

#include <sys/types.h>

/* Convert a PCI busId string into a local cudaDev device index (cf. CUDA_VISIBLE_DEVICES) */
static int busIdToCudaDev(int64_t busId) {
  int ndev;
  if (cudaGetDeviceCount(&ndev) != cudaSuccess)
    return -1;
  for (int i = 0; i < ndev; i++) {
    char devBusIdStr[NVML_DEVICE_PCI_BUS_ID_BUFFER_SIZE];
    if (cudaDeviceGetPCIBusId(devBusIdStr, NVML_DEVICE_PCI_BUS_ID_BUFFER_SIZE, i) != cudaSuccess)
      return -1;
    int64_t devBusId;
    NCCLCHECK(busIdToInt64(devBusIdStr, &devBusId));
    if (busId == devBusId) return i;
  }
  // BusId was not found in our locally visible CUDA devices
  return -1;
}

NCCL_PARAM(P2pUseCudaMemcpy, "P2P_USE_CUDA_MEMCPY", 0);
static int useMemcpy = 0;
static void initCeOperation();

/* Determine if two peers can communicate through p2p */
ncclResult_t p2pCanConnect(int* ret, struct ncclTopoSystem* topo, struct ncclTopoGraph* graph, struct ncclPeerInfo* info1, struct ncclPeerInfo* info2) {
  initCeOperation();
#if defined(__HIP_PLATFORM_HCC__) || defined(__HCC__) || defined(__HIPCC__)
  if (!info1->hasFineGrain || !info2->hasFineGrain)  {
    *ret = 0;
    return ncclSuccess;
  }
#endif

  // Rule out different nodes / isolated containers
  if (info1->hostHash != info2->hostHash || info1->shmDev != info2->shmDev) {
    *ret = 0;
    return ncclSuccess;
  }

  // Check topology / p2p level.
  int intermediateRank;
  NCCLCHECK(ncclTopoCheckP2p(topo, info1->busId, info2->busId, ret, NULL, &intermediateRank));
  if (*ret == 0) return ncclSuccess;
  if (intermediateRank != -1) {
    if (useMemcpy) *ret = 0;
    return ncclSuccess;
  }

  // Check if NET would work better
  int useNet = 0;
  NCCLCHECK(ncclTopoCheckNet(topo, info1->busId, info2->busId, &useNet));
  if (useNet) {
    *ret = 0;
    return ncclSuccess;
  }

  // Convert the peer's busId into a local cudaDev index (cf. CUDA_VISIBLE_DEVICES)
  int cudaDev1 = busIdToCudaDev(info1->busId);
  int cudaDev2 = busIdToCudaDev(info2->busId);
  if (cudaDev1 == -1 || cudaDev2 == -1) {
#if defined(__HIP_PLATFORM_HCC__) || defined(__HCC__) || defined(__HIPCC__) || CUDART_VERSION >= 10010
    // CUDA 10.1 and later can use P2P with invisible devices.
    return ncclSuccess;
#else
    // Peer's CUDA device is not visible in this process : we can't communicate with it.
    *ret = 0;
    return ncclSuccess;
#endif
  }

  // Check that CUDA can do P2P
  int p2p;
  if (cudaDeviceCanAccessPeer(&p2p, cudaDev1, cudaDev2) != cudaSuccess) {
    INFO(NCCL_INIT|NCCL_P2P,"peer query failed between dev %d(=%lx) and dev %d(=%lx)",
         cudaDev1, info1->busId, cudaDev2, info2->busId);
    *ret = 0;
    return ncclSuccess;
  }
  if (p2p == 0 && cudaDev1 == cudaDev2 && info1->busId == info2->busId) {
    p2p = 1;
  }

#if defined(__HIP_PLATFORM_HCC__) || defined(__HCC__) || defined(__HIPCC__)
#else
  // Check that legacy IPC support is available
  if (p2p != 0) {
    // Cached result of the legacyIPC detection
    static int legacyIPC = -1;
    if (legacyIPC >= 0) {
      *ret = legacyIPC;
      return ncclSuccess;
    }
    // Check that legacy IPC support is available (WSL WAR)
    char *dummy;
    cudaIpcMemHandle_t ipc;
    NCCLCHECK(ncclCudaCalloc(&dummy, CUDA_IPC_MIN));
    if (cudaIpcGetMemHandle(&ipc, dummy) != cudaSuccess) {
      INFO(NCCL_INIT|NCCL_P2P,"Legacy IPC not supported");
      *ret = 0;
    }
    CUDACHECK(cudaFree(dummy));
    legacyIPC = *ret;
    return ncclSuccess;
  }
#endif

  if (p2p == 0) {
    INFO(NCCL_INIT|NCCL_P2P,"Could not enable P2P between dev %d(=%lx) and dev %d(=%lx)",
         cudaDev1, info1->busId, cudaDev2, info2->busId);
    *ret = 0;
    return ncclSuccess;
  }
  return ncclSuccess;
}

#define TRACE_DUMP_IPC(DEVIPC)                                                             \
  do {                                                                                     \
    unsigned long *devIpc = (unsigned long *) (DEVIPC);                                    \
    TRACE(P2P,"IPC: %016lx %016lx %016lx %016lx", devIpc[0], devIpc[1], devIpc[2], devIpc[3]); \
    TRACE(P2P,"IPC: %016lx %016lx %016lx %016lx", devIpc[4], devIpc[5], devIpc[6], devIpc[7]); \
  } while (0)


// Setting this to non zero causes P2P to use Reads rather than Writes
NCCL_PARAM(P2pReadEnable, "P2P_READ_ENABLE", -2);
NCCL_PARAM(P2pDirectDisable, "P2P_DIRECT_DISABLE", 0);

static ncclResult_t p2pGetInfo(struct ncclTopoSystem* topo, struct ncclPeerInfo* info1, struct ncclPeerInfo* info2, int* read, int* intermediateRank) {
  int p2p;
  // Queries the topology to see if the GPUs are Ampere and
  // connected via NVLink, if so we enable P2P Read by default
  NCCLCHECK(ncclTopoCheckP2p(topo, info1->busId, info2->busId, &p2p, read, intermediateRank));

  int readEnable = ncclParamP2pReadEnable();
  if (readEnable != -2) *read = readEnable;
  return ncclSuccess;
}

static ncclResult_t p2pMap(struct ncclPeerInfo* myInfo, struct ncclPeerInfo* peerInfo, struct ncclP2pBuff* p2pBuff, void** devMem, void** ipcPtr) {
  if (myInfo->pidHash == peerInfo->pidHash) {
    if (peerInfo->cudaDev != myInfo->cudaDev) {
      // Enable P2P access
      cudaError_t err = cudaDeviceEnablePeerAccess(peerInfo->cudaDev, 0);
      if (err == cudaErrorPeerAccessAlreadyEnabled) {
        cudaGetLastError();
      } else if (err != cudaSuccess) {
        WARN("failed to peer with device %d(=%lx): %d %s",
            peerInfo->cudaDev, peerInfo->busId, err, cudaGetErrorString(err));
        return ncclInternalError;
      }
    }
    *devMem = p2pBuff->directPtr;
    *ipcPtr = NULL;
  } else {
    CUDACHECK(cudaIpcOpenMemHandle(devMem, p2pBuff->devIpc, cudaIpcMemLazyEnablePeerAccess));
    *ipcPtr = *devMem;
  }
  return ncclSuccess;
}

/* Send: Create and return connect structures for this peer to connect to me */
ncclResult_t p2pSendSetup(struct ncclComm* comm, struct ncclTopoGraph* graph, struct ncclPeerInfo* myInfo, struct ncclPeerInfo* peerInfo,
    struct ncclConnect* connectInfo, struct ncclConnector* send, int channelId, int connIndex) {
  struct p2pSendResources* resources;
  NCCLCHECK(ncclCalloc(&resources, 1));
  send->transportResources = resources;
  int useRead, intermediateRank;
  NCCLCHECK(p2pGetInfo(comm->topo, myInfo, peerInfo, &useRead, &intermediateRank));
  if (useMemcpy) useRead = 0;

  resources->next_hdp_reg = 0;
  bool isXGMI;
  if (ncclTopoGetLinkType(comm->topo, myInfo->cudaDev, peerInfo->cudaDev, &isXGMI) != ncclSuccess) {
    INFO(NCCL_INIT|NCCL_P2P,"Ring %02d : %d -> %d failed to get link type and hop count", channelId, myInfo->rank, peerInfo->rank);
    return ncclInternalError;
  }
  if (!isXGMI && comm->topo->nodes[GPU].nodes[0].gpu.gcn != 910 && comm->topo->nodes[GPU].nodes[0].gpu.gcn/10 != 94) {
    CUDACHECK(hipDeviceGetAttribute((int*)&resources->next_hdp_reg, hipDeviceAttributeHdpMemFlushCntl,peerInfo->cudaDev));
    TRACE(NCCL_INIT|NCCL_P2P,"Ring %02d : %d -> %d HDP %p", channelId, myInfo->rank, peerInfo->rank, resources->next_hdp_reg);
  }

  static_assert(sizeof(struct p2pConnectInfo) <= sizeof(struct ncclConnect), "p2p Connect Info is too big");
  struct p2pConnectInfo* info = (struct p2pConnectInfo*)connectInfo;
  info->read = useRead;
  // For CollNet, use write for scatter-reduce (conn 1), read for broadcast-gather (conn 0)
  if (graph && connIndex == 1) info->read = 0;
  const char* useReadStr = info->read ? "/read" : "";

  int sendSize = sizeof(struct ncclSendMem);
  // For P2P Read the SIMPLE buffer is tagged on the end of the ncclSendMem structure
  if (info->read) sendSize += send->comm->buffSizes[NCCL_PROTO_SIMPLE];
  ALIGN_SIZE(sendSize, CUDA_IPC_MIN);

  if (intermediateRank == -1) {
    info->rank = myInfo->rank;
    if (myInfo->pidHash == peerInfo->pidHash && useMemcpy == 0) {
      if (ncclParamP2pDirectDisable() == 0) send->conn.flags |= info->read ? NCCL_DIRECT_READ : NCCL_DIRECT_WRITE;
      INFO(NCCL_INIT|NCCL_P2P, "Channel %02d/%01d : %d[%lx] -> %d[%lx] via P2P/direct pointer%s comm %p nRanks %02d",
          channelId, connIndex, myInfo->rank, myInfo->busId, peerInfo->rank, peerInfo->busId, useReadStr, comm, comm->nRanks);
    } else {
      send->conn.flags |= info->read ? NCCL_IPC_READ : NCCL_IPC_WRITE;
      INFO(NCCL_INIT|NCCL_P2P,"Channel %02d/%01d : %d[%lx] -> %d[%lx] via P2P/IPC%s%s comm %p nRanks %02d",
          channelId, connIndex, myInfo->rank, myInfo->busId, peerInfo->rank, peerInfo->busId, useReadStr, useMemcpy ? "/CE" : "", comm, comm->nRanks);
    }
  } else {
    info->rank = intermediateRank;
    INFO(NCCL_INIT|NCCL_P2P, "Channel %02d/%01d : %d[%lx] -> %d[%lx] via P2P/indirect/%d[%lx]%s comm %p nRanks %02d",
        channelId, connIndex, myInfo->rank, myInfo->busId, peerInfo->rank, peerInfo->busId, intermediateRank,
	comm->peerInfo[intermediateRank].busId, useReadStr, comm, comm->nRanks);
  }

  NCCLCHECK(ncclProxyConnect(comm, TRANSPORT_P2P, 1, info->rank, &send->proxyConn));
  if (useMemcpy) {
    NCCLCHECK(ncclProxyCallBlocking(&send->proxyConn, ncclProxyMsgSetup, NULL, 0, &resources->proxyInfo, sizeof(struct p2pProxyInfo)));
    info->shmSize = resources->proxyInfo.shmSize;
    memcpy(info->shmName, resources->proxyInfo.shmName, sizeof(info->shmName));
  } else {
    NCCLCHECK(ncclProxyCallBlocking(&send->proxyConn, ncclProxyMsgSetup, &sendSize, sizeof(int), &info->p2pBuff, sizeof(struct ncclP2pBuff)));
    NCCLCHECK(p2pMap(myInfo, comm->peerInfo+info->rank, &info->p2pBuff, (void**)&resources->devMem, &resources->sendMemIpc));
  }

  return ncclSuccess;
}

/* Create and return connect structures for this peer to connect to me */
ncclResult_t p2pRecvSetup(struct ncclComm* comm, struct ncclTopoGraph* graph, struct ncclPeerInfo* myInfo, struct ncclPeerInfo* peerInfo,
    struct ncclConnect* connectInfo, struct ncclConnector * recv, int channelId, int connIndex) {
  struct p2pRecvResources* resources;
  NCCLCHECK(ncclCalloc(&resources, 1));
  recv->transportResources = resources;
  int useRead, intermediateRank;
  NCCLCHECK(p2pGetInfo(comm->topo, myInfo, peerInfo, &useRead, &intermediateRank));

  static_assert(sizeof(struct p2pConnectInfo) <= sizeof(struct ncclConnect), "p2p Connect Info is too big");
  struct p2pConnectInfo* info = (struct p2pConnectInfo*)connectInfo;
  info->read = useRead;
  // For CollNet, use write for scatter-reduce (conn 1), read for broadcast-gather (conn 0)
  if (graph && connIndex == 1) info->read = 0;

  int recvSize = sizeof(struct ncclRecvMem);
  // For P2P Read the SIMPLE buffer is tagged on the end of the ncclSendMem structure
  for (int p=0; p<NCCL_NUM_PROTOCOLS; p++) if (!(info->read && p == NCCL_PROTO_SIMPLE)) recvSize += recv->comm->buffSizes[p];
  ALIGN_SIZE(recvSize, CUDA_IPC_MIN);

  if (intermediateRank == -1) {
    info->rank = myInfo->rank;
    if (myInfo->pidHash == peerInfo->pidHash && useMemcpy == 0) {
      if (ncclParamP2pDirectDisable() == 0) recv->conn.flags |= info->read ? NCCL_DIRECT_READ : NCCL_DIRECT_WRITE;
    } else {
      recv->conn.flags |= info->read ? NCCL_IPC_READ : NCCL_IPC_WRITE;
    }
  } else {
    info->rank = intermediateRank;
  }

  NCCLCHECK(ncclProxyConnect(comm, TRANSPORT_P2P, 0, info->rank, &recv->proxyConn));
  NCCLCHECK(ncclProxyCallBlocking(&recv->proxyConn, ncclProxyMsgSetup, &recvSize, sizeof(int), &info->p2pBuff, sizeof(struct ncclP2pBuff)));

  NCCLCHECK(p2pMap(myInfo, comm->peerInfo+info->rank, &info->p2pBuff, (void**)&resources->devMem, &resources->recvMemIpc));
  return ncclSuccess;
}

/* Connect/Send to this peer */
static ncclResult_t p2pSendConnect(struct ncclComm* comm, struct ncclConnect* connectInfo, int nranks, int rank, struct ncclConnector* send) {
  struct p2pSendResources* resources = (struct p2pSendResources*)send->transportResources;
  struct ncclRecvMem* remDevMem;
  struct p2pConnectInfo* info = (struct p2pConnectInfo*)connectInfo;

  NCCLCHECK(p2pMap(comm->peerInfo+rank, comm->peerInfo+info->rank, &info->p2pBuff, (void**)&remDevMem, &resources->recvMemIpc));

  char* buff = (char*)(remDevMem+1);
  for (int p=0; p<NCCL_NUM_PROTOCOLS; p++) {
    if (info->read && p == NCCL_PROTO_SIMPLE) {
      /* For P2P Read the SIMPLE buffer is local (ncclSendMem) */
      if (resources->devMem == NULL) return ncclInternalError; // We should not use read + memcpy
      send->conn.buffs[p] = (char*)(resources->devMem+1);
    } else {
      send->conn.buffs[p] = buff;
      buff += send->comm->buffSizes[p];
    }
  }

  if (useMemcpy) {
    send->conn.tail = &resources->proxyInfo.ceRecvMem->tail;
    send->conn.sizesFifo = resources->proxyInfo.ceRecvMem->sizesFifo;
    send->conn.head = &resources->proxyInfo.devShm->sendMem.head;
    // Send SIMPLE buff to proxy, and replace it by local buffer
    NCCLCHECK(ncclProxyCallBlocking(&send->proxyConn, ncclProxyMsgConnect, &send->conn.buffs[NCCL_PROTO_SIMPLE], sizeof(void*), NULL, 0));
    send->conn.buffs[NCCL_PROTO_SIMPLE] = resources->proxyInfo.ceDevBuff;
  } else {
    send->conn.tail = &remDevMem->tail;
    send->conn.head = &resources->devMem->head;
    send->conn.ptrExchange = &resources->devMem->ptrExchange;
    send->conn.redOpArgExchange = resources->devMem->redOpArgExchange;
  }
  return ncclSuccess;
}

/* Connect/Recv from this peer */
ncclResult_t p2pRecvConnect(struct ncclComm* comm, struct ncclConnect* connectInfo, int nranks, int rank, struct ncclConnector* recv) {
  struct p2pRecvResources* resources = (struct p2pRecvResources*)recv->transportResources;
  struct p2pConnectInfo* info = (struct p2pConnectInfo*)connectInfo;

  struct ncclSendMem* remDevMem = NULL;

  if (useMemcpy) {
    char shmPath[PATH_MAX];
    sprintf(shmPath, "/dev/shm/nccl-%s", info->shmName);
    TRACE(NCCL_SHM,"Open shmName %s shmSize %d", shmPath, info->shmSize);
    resources->shmSize = info->shmSize;
    NCCLCHECK(ncclShmOpen(shmPath, info->shmSize, (void**)&resources->shm, (void**)&resources->devShm, -1, &resources->handle));

    recv->conn.tail = &resources->devShm->recvMem.tail;
    recv->conn.head = &resources->devShm->sendMem.head;
  } else {
    NCCLCHECK(p2pMap(comm->peerInfo+rank, comm->peerInfo+info->rank, &info->p2pBuff, (void**)&remDevMem, &resources->sendMemIpc));

    recv->conn.tail = &resources->devMem->tail;
    recv->conn.head = &remDevMem->head;
    recv->conn.ptrExchange = &remDevMem->ptrExchange;
    recv->conn.redOpArgExchange = remDevMem->redOpArgExchange;
  }

  char* buff = (char*)(resources->devMem+1);
  for (int p=0; p<NCCL_NUM_PROTOCOLS; p++) {
    if (info->read && p == NCCL_PROTO_SIMPLE) {
      if (remDevMem == NULL) return ncclInternalError; // We should not use read + memcpy
      /* For P2P Read the SIMPLE buffer is remote (ncclSendMem) */
      recv->conn.buffs[p] = (char*)(remDevMem+1);
    } else {
      recv->conn.buffs[p] = buff;
      buff += recv->comm->buffSizes[p];
    }
  }
  return ncclSuccess;
}

ncclResult_t p2pSendFree(struct ncclConnector* send) {
  struct p2pSendResources* resources = (struct p2pSendResources*)send->transportResources;
  if (resources) {
    if (resources->sendMemIpc) CUDACHECK(cudaIpcCloseMemHandle(resources->sendMemIpc));
    if (resources->recvMemIpc) CUDACHECK(cudaIpcCloseMemHandle(resources->recvMemIpc));
    free(resources);
  }
  return ncclSuccess;
}

ncclResult_t p2pRecvFree(struct ncclConnector* recv) {
  struct p2pRecvResources* resources = (struct p2pRecvResources*)recv->transportResources;
  if (resources) {
    if (resources->sendMemIpc) CUDACHECK(cudaIpcCloseMemHandle(resources->sendMemIpc));
    if (resources->recvMemIpc) CUDACHECK(cudaIpcCloseMemHandle(resources->recvMemIpc));
    if (useMemcpy) {
      NCCLCHECK(ncclShmClose(resources->handle));
    }
    free(resources);
  }
  return ncclSuccess;
}

static ncclResult_t p2pSendProxySetup(struct ncclProxyConnection* connection, struct ncclComm* comm, void* reqBuff, int reqSize, void* respBuff, int respSize, int* done) {
  if (useMemcpy) {
    struct p2pProxyInfo* proxyInfo;
    NCCLCHECK(ncclCalloc(&proxyInfo, 1));
    connection->transportResources = proxyInfo;

    NCCLCHECK(ncclCudaCalloc(&proxyInfo->ceDevBuff, comm->buffSizes[NCCL_PROTO_SIMPLE], comm->sideStream, true));

    char shmPath[PATH_MAX];
    shmPath[0] = '\0';
    proxyInfo->shmSize = sizeof(struct ncclSendMem) + sizeof(struct ncclRecvMem);
    NCCLCHECK(ncclShmOpen(shmPath, proxyInfo->shmSize, (void**)&proxyInfo->shm, (void**)&proxyInfo->devShm, 1, &proxyInfo->handle));
    TRACE(NCCL_SHM,"Opened shmName %s shmSize %d", shmPath, proxyInfo->shmSize);
    memcpy(proxyInfo->shmName, shmPath+sizeof("/dev/shm/nccl-")-1, sizeof(proxyInfo->shmName));

    NCCLCHECK(ncclCudaHostCalloc(&proxyInfo->ceRecvMem, 1));

    if (respSize != sizeof(struct p2pProxyInfo)) return ncclInternalError;
    memcpy(respBuff, proxyInfo, sizeof(struct p2pProxyInfo));
  } else {
    if (reqSize != sizeof(int)) return ncclInternalError;
    int size = *((int*)reqBuff);
    if (respSize != sizeof(struct ncclP2pBuff)) return ncclInternalError;
    struct ncclP2pBuff* p2pBuff = (struct ncclP2pBuff*)respBuff;
    NCCLCHECK(ncclCudaCalloc((char**)&p2pBuff->directPtr, size, comm->sideStream, true));
    connection->transportResources = p2pBuff->directPtr;
    cudaError_t res = cudaIpcGetMemHandle(&p2pBuff->devIpc, p2pBuff->directPtr);
    if (res != cudaSuccess) {
      WARN("cudaIpcGetMemHandle failed : %s", cudaGetErrorString(res));
      cudaFree(p2pBuff->directPtr);
      free(p2pBuff);
      CUDACHECK(res);
    }
  }
  *done = 1;
  return ncclSuccess;
}

static ncclResult_t p2pRecvProxySetup(struct ncclProxyConnection* connection, struct ncclComm* comm, void* reqBuff, int reqSize, void* respBuff, int respSize, int* done) {
  if (reqSize != sizeof(int)) return ncclInternalError;
  int size = *((int*)reqBuff);
  if (respSize != sizeof(struct ncclP2pBuff)) return ncclInternalError;
  struct ncclP2pBuff* p2pBuff = (struct ncclP2pBuff*)respBuff;
  NCCLCHECK(ncclCudaCalloc((char**)&p2pBuff->directPtr, size, comm->sideStream, true));
  connection->transportResources = p2pBuff->directPtr;
  cudaError_t res = cudaIpcGetMemHandle(&p2pBuff->devIpc, p2pBuff->directPtr);
  if (res != cudaSuccess) {
    WARN("cudaIpcGetMemHandle failed : %s", cudaGetErrorString(res));
    cudaFree(p2pBuff->directPtr);
    free(p2pBuff);
    CUDACHECK(res);
  }
  *done = 1;
  return ncclSuccess;
}

static ncclResult_t p2pSendProxyConnect(struct ncclProxyConnection* connection, struct ncclComm* comm, void* reqBuff, int reqSize, void* respBuff, int respSize, int* done) {
  struct p2pProxyInfo* proxyInfo = (struct p2pProxyInfo*)connection->transportResources;

  if (reqSize != sizeof(void*)) return ncclInternalError;
  proxyInfo->recvFifo = *((char**)reqBuff);

  CUDACHECK(cudaStreamCreateWithFlags(&proxyInfo->stream, cudaStreamNonBlocking));
  for (int i=0; i<NCCL_STEPS; i++) {
    CUDACHECK(cudaEventCreate(proxyInfo->events+i));
  }
  connection->proxyAppendPtr = &connection->proxyAppend;
  return ncclSuccess;
}

static ncclResult_t p2pSendProxyFree(struct ncclProxyConnection* connection, struct ncclComm* comm) {
  if (useMemcpy) {
    struct p2pProxyInfo* proxyInfo = (struct p2pProxyInfo*)connection->transportResources;
    if (proxyInfo) {
      NCCLCHECK(ncclShmClose(proxyInfo->handle));
      NCCLCHECK(ncclCudaHostFree(proxyInfo->ceRecvMem));
      CUDACHECK(cudaFree(proxyInfo->ceDevBuff));
      CUDACHECK(cudaStreamDestroy(proxyInfo->stream));
      for (int i=0; i<NCCL_STEPS; i++) {
        CUDACHECK(cudaEventDestroy(proxyInfo->events[i]));
      }
      free(proxyInfo);
    }
  } else {
    // Do not check return code as CUDA may have already shut down
    cudaFree(connection->transportResources);
  }
  return ncclSuccess;
}

static ncclResult_t p2pRecvProxyFree(struct ncclProxyConnection* connection, struct ncclComm* comm) {
  // Do not check return code as CUDA may have already shut down
  cudaFree(connection->transportResources);
  return ncclSuccess;
}

static ncclResult_t p2pSendProxyProgress(struct ncclComm* comm, struct ncclProxyArgs* args) {
  if (args->state == ncclProxyOpReady) {
    for (int s=0; s<args->nsubs; s++) {
      struct ncclProxySubArgs* sub = args->subs+s;
      struct p2pProxyInfo* resources = (struct p2pProxyInfo*) (sub->connection->transportResources);
      // Round to next multiple of sliceSteps
      sub->base = ROUNDUP(resources->step, args->chunkSteps);
      sub->posted = sub->transmitted = sub->done = 0;
    }
    args->state = ncclProxyOpProgress;
  }
  args->idle = 1;
  if (args->state == ncclProxyOpProgress) {
    int p = args->protocol;
    int stepSize = comm->buffSizes[p] / NCCL_STEPS;
    for (int s=0; s<args->nsubs; s++) {
      struct ncclProxySubArgs* sub = args->subs+s;
      struct p2pProxyInfo* resources = (struct p2pProxyInfo*) (sub->connection->transportResources);
      if (p != NCCL_PROTO_SIMPLE) { // Only Simple uses cudaMemcpy
          resources->step = sub->base + sub->nsteps;
          args->done++;
          continue;
      }
      if (sub->transmitted < sub->done + NCCL_STEPS && sub->transmitted < sub->nsteps) {
        int buffSlot = (sub->base+sub->transmitted)%NCCL_STEPS;
        volatile int* sizesFifo = resources->ceRecvMem->sizesFifo;
        volatile uint64_t* recvTail = &resources->ceRecvMem->tail;
        // Check GPU has sent everything
        if ((*recvTail > sub->base+sub->transmitted)) {
          int size = sizesFifo[buffSlot];
          CUDACHECK(cudaMemcpyAsync(resources->recvFifo+buffSlot*stepSize, resources->ceDevBuff+buffSlot*stepSize, size, cudaMemcpyDeviceToDevice, resources->stream));
          CUDACHECK(cudaEventRecord(resources->events[buffSlot], resources->stream));
          sub->transmitted += args->sliceSteps;
        }
      }
      if (sub->done < sub->transmitted) {
        int buffSlot = (sub->base+sub->done)%NCCL_STEPS;
        cudaError_t res = cudaEventQuery(resources->events[buffSlot]);
        if (res != cudaErrorNotReady) CUDACHECK(res);
        if (res == cudaSuccess) {
          sub->done += args->sliceSteps;
          // Notify SHM
          resources->shm->recvMem.tail = sub->base + sub->done;
        }
        if (sub->done == sub->nsteps) {
          resources->step = sub->base + sub->nsteps;
          args->done++;
        }
      }
    }
    if (args->done == args->nsubs) {
      args->state = ncclProxyOpNone;
    }
  }
  return ncclSuccess;
}

struct ncclTransport p2pTransport = {
  "P2P",
  p2pCanConnect,
  { p2pSendSetup, p2pSendConnect, p2pSendFree, NULL, p2pSendProxySetup, NULL, p2pSendProxyFree, NULL },
  { p2pRecvSetup, p2pRecvConnect, p2pRecvFree, NULL, p2pRecvProxySetup, NULL, p2pRecvProxyFree, NULL }
};

static void initCeOperation() {
  static int init = 0;
  if (!init) {
    useMemcpy = ncclParamP2pUseCudaMemcpy();
    if (useMemcpy) {
      p2pTransport.send.proxyConnect = p2pSendProxyConnect;
      p2pTransport.send.proxyProgress = p2pSendProxyProgress;
    }
    init = 1;
  }
}
