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Use poll to avoid busy loops for bootstrap socket-io #1759

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Use poll to avoid busy loops for bootstrap socket-io #1759

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16 changes: 15 additions & 1 deletion src/misc/socket.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,8 @@

NCCL_PARAM(RetryCnt, "SOCKET_RETRY_CNT", 34);
NCCL_PARAM(RetryTimeOut, "SOCKET_RETRY_SLEEP_MSEC", 100);
NCCL_PARAM(PollTimeOut, "SOCKET_POLL_TIMEOUT_MSEC", 0);

static void msleep(unsigned int time_msec) {
const long c_1e6 = 1e6;
struct timespec tv = (struct timespec){
Expand All @@ -25,6 +27,14 @@ static void msleep(unsigned int time_msec) {
nanosleep(&tv, NULL);
}

static void pollSocket(int fd, int op) {
struct pollfd pfd;
pfd.fd = fd;
pfd.events = (op == NCCL_SOCKET_RECV) ? POLLIN : POLLOUT;
pfd.revents = 0;
poll(&pfd, 1, ncclParamPollTimeOut());
}

static ncclResult_t socketProgressOpt(int op, struct ncclSocket* sock, void* ptr, int size, int* offset, int block, int* closed) {
int bytes = 0;
*closed = 0;
Expand Down Expand Up @@ -77,8 +87,12 @@ static ncclResult_t socketProgress(int op, struct ncclSocket* sock, void* ptr, i
}

static ncclResult_t socketWait(int op, struct ncclSocket* sock, void* ptr, int size, int* offset) {
while (*offset < size)
while (*offset < size) {
NCCLCHECK(socketProgress(op, sock, ptr, size, offset));
// If we have more data to read or write, use the poll system call to wait
// until the socket becomes readable or writable again.
if ((*offset < size) && ncclParamPollTimeOut()) pollSocket(sock->fd, op);
}
return ncclSuccess;
}

Expand Down