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/*************************************************************************
* Copyright (c) 2016-2018, NVIDIA CORPORATION. All rights reserved.
*
* See LICENSE.txt for license information
************************************************************************/
#ifndef NCCL_SHM_H_
#define NCCL_SHM_H_
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
// Change functions behavior to match other SYS functions
static int shm_allocate(int fd, const int shmsize) {
int err = posix_fallocate(fd, 0, shmsize);
if (err) { errno = err; return -1; }
return 0;
}
static int shm_map(int fd, const int shmsize, void** ptr) {
*ptr = mmap(NULL, shmsize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
return (*ptr == MAP_FAILED) ? -1 : 0;
}
static ncclResult_t shmSetup(const char* shmname, const int shmsize, int* fd, void** ptr, int create) {
SYSCHECKVAL(shm_open(shmname, O_CREAT | O_RDWR, S_IRUSR | S_IWUSR), "shm_open", *fd);
if (create) SYSCHECK(shm_allocate(*fd, shmsize), "posix_fallocate");
SYSCHECK(shm_map(*fd, shmsize, ptr), "mmap");
close(*fd);
*fd = -1;
if (create) memset(*ptr, 0, shmsize);
return ncclSuccess;
}
static ncclResult_t shmOpen(const char* shmname, const int shmsize, void** shmPtr, void** devShmPtr, int create) {
int fd = -1;
void* ptr = MAP_FAILED;
ncclResult_t res = ncclSuccess;
NCCLCHECKGOTO(shmSetup(shmname, shmsize, &fd, &ptr, create), res, sysError);
CUDACHECKGOTO(cudaHostRegister(ptr, shmsize, cudaHostRegisterMapped), res, cudaError);
CUDACHECKGOTO(cudaHostGetDevicePointer(devShmPtr, ptr, 0), res, cudaError);
*shmPtr = ptr;
return ncclSuccess;
sysError:
WARN("Error while %s shared memory segment %s (size %d)\n", create ? "creating" : "attaching to", shmname, shmsize);
cudaError:
if (fd != -1) close(fd);
if (create) shm_unlink(shmname);
if (ptr != MAP_FAILED) munmap(ptr, shmsize);
*shmPtr = NULL;
return res;
}
static ncclResult_t shmUnlink(const char* shmname) {
if (shmname != NULL) SYSCHECK(shm_unlink(shmname), "shm_unlink");
return ncclSuccess;
}
static ncclResult_t shmClose(void* shmPtr, void* devShmPtr, const int shmsize) {
CUDACHECK(cudaHostUnregister(shmPtr));
if (munmap(shmPtr, shmsize) != 0) {
WARN("munmap of shared memory failed");
return ncclSystemError;
}
return ncclSuccess;
}
#endif
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