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rdma_transport.h
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rdma_transport.h
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// Copyright 2019 Bytedance Inc. or its affiliates. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// =============================================================================
#ifndef PS_RDMA_TRANSPORT_H_
#define PS_RDMA_TRANSPORT_H_
#ifdef DMLC_USE_RDMA
#include "rdma_utils.h"
namespace ps {
class Postoffice;
class Transport;
struct Endpoint {
enum ConnectionStatus { IDLE, CONNECTING, CONNECTED, REJECTED };
ConnectionStatus status;
int node_id;
std::condition_variable cv;
std::mutex connect_mu;
struct rdma_cm_id *cm_id;
std::shared_ptr<Transport> trans;
int kStartDepth = 128;
int kRxDepth = 2048;
int kReplyDepth = kRxDepth;
WRContext *rx_ctx;
WRContext *start_ctx;
WRContext *reply_ctx;
ThreadsafeQueue<WRContext *> free_start_ctx;
ThreadsafeQueue<WRContext *> free_reply_ctx;
bool inited = false;
Endpoint() : status(IDLE), node_id(Node::kEmpty), cm_id(nullptr), rx_ctx() {
auto byteps_rx_depth = Environment::Get()->find("BYTEPS_RDMA_RX_DEPTH");
auto byteps_start_depth =
Environment::Get()->find("BYTEPS_RDMA_START_DEPTH");
const char *role_val = CHECK_NOTNULL(Environment::Get()->find("DMLC_ROLE"));
std::string role_str(role_val);
// for joint mode with large number of workers, the default value of rx/tx
// depth is reduced for less memory consumption.
if (role_str == "scheduler") {
kStartDepth = 256;
kRxDepth = 16;
}
kStartDepth = byteps_start_depth ? atoi(byteps_start_depth) : kStartDepth;
kRxDepth = byteps_rx_depth ? atoi(byteps_rx_depth) : kRxDepth;
kReplyDepth = kRxDepth;
start_ctx = new WRContext[kStartDepth];
reply_ctx = new WRContext[kReplyDepth];
rx_ctx = new WRContext[kRxDepth];
}
~Endpoint() {
for (int i = 0; i < kRxDepth; ++i) {
if (!(rx_ctx[i].buffer)) {
continue;
}
free(rx_ctx[i].buffer->addr);
CHECK_EQ(ibv_dereg_mr(rx_ctx[i].buffer), 0);
}
for (int i = 0; i < kStartDepth; ++i) {
if (start_ctx[i].buffer) {
free(start_ctx[i].buffer->addr);
CHECK_EQ(ibv_dereg_mr(start_ctx[i].buffer), 0);
}
}
for (int i = 0; i < kReplyDepth; ++i) {
if (reply_ctx[i].buffer) {
free(reply_ctx[i].buffer->addr);
CHECK_EQ(ibv_dereg_mr(reply_ctx[i].buffer), 0);
}
}
rdma_destroy_qp(cm_id);
CHECK_EQ(rdma_destroy_id(cm_id), 0) << strerror(errno);
}
void SetTransport(std::shared_ptr<Transport> t) { trans = t; }
std::shared_ptr<Transport> GetTransport() { return trans; }
void Disconnect() {
std::unique_lock<std::mutex> lk(connect_mu);
CHECK_EQ(rdma_disconnect(cm_id), 0) << strerror(errno);
cv.wait(lk, [this] { return status == IDLE; });
trans.reset();
}
void SetNodeID(int id) { node_id = id; }
void InitSendContextHelper(struct ibv_pd *pd, WRContext *ctx,
ThreadsafeQueue<WRContext *> *queue, size_t num,
WRContextType type) {
for (size_t i = 0; i < num; ++i) {
void *buf;
aligned_malloc((void **)&buf, kMempoolChunkSize);
CHECK(buf);
struct ibv_mr *mr = ibv_reg_mr(pd, buf, kMempoolChunkSize, 0);
CHECK(mr) << "ibv_reg_mr failed: " << strerror(errno)
<< "\nYou can try to reduce BYTEPS_RDMA_START_DEPTH (current "
<< kStartDepth << ") or BYTEPS_RDMA_RX_DEPTH (current "
<< kRxDepth << ").";
ctx[i].type = type;
ctx[i].buffer = mr;
ctx[i].private_data = this;
queue->Push(&ctx[i]);
}
}
void Init(struct ibv_cq *cq, struct ibv_pd *pd) {
struct ibv_qp_init_attr attr;
memset(&attr, 0, sizeof(ibv_qp_init_attr));
attr.send_cq = cq;
attr.recv_cq = cq;
attr.cap.max_send_wr = kStartDepth + kReplyDepth;
attr.cap.max_recv_wr = kRxDepth;
attr.cap.max_send_sge = kSGEntry;
attr.cap.max_recv_sge = kSGEntry;
attr.qp_type = IBV_QPT_RC;
attr.sq_sig_all = 0;
CHECK_EQ(rdma_create_qp(cm_id, pd, &attr), 0)
<< "Create RDMA queue pair failed: " << strerror(errno);
if (inited == false) {
InitSendContextHelper(pd, start_ctx, &free_start_ctx, kStartDepth,
kRendezvousStartContext);
InitSendContextHelper(pd, reply_ctx, &free_reply_ctx, kReplyDepth,
kRendezvousReplyContext);
}
for (int i = 0; i < kRxDepth; ++i) {
if (inited == false) {
void *buf;
aligned_malloc((void **)&buf, kMempoolChunkSize);
CHECK(buf);
struct ibv_mr *mr =
ibv_reg_mr(pd, buf, kMempoolChunkSize, IBV_ACCESS_LOCAL_WRITE);
CHECK(mr)
<< "ibv_reg_mr failed: " << strerror(errno)
<< "\nYou can try to reduce BYTEPS_RDMA_START_DEPTH (default 128)"
<< " or BYTEPS_RDMA_RX_DEPTH (default 2048)";
rx_ctx[i].type = kReceiveContext;
rx_ctx[i].buffer = mr;
rx_ctx[i].private_data = this;
}
PostRecv(&rx_ctx[i]);
}
inited = true;
}
void PostRecv(WRContext *ctx) {
struct ibv_recv_wr wr, *bad_wr = nullptr;
memset(&wr, 0, sizeof(wr));
struct ibv_sge sge;
sge.addr = reinterpret_cast<uint64_t>(ctx->buffer->addr);
sge.length = kMempoolChunkSize;
sge.lkey = ctx->buffer->lkey;
wr.wr_id = reinterpret_cast<uint64_t>(ctx);
wr.next = nullptr;
wr.sg_list = &sge;
wr.num_sge = 1;
CHECK_EQ(ibv_post_recv(cm_id->qp, &wr, &bad_wr), 0)
<< "ibv_post_recv failed.";
}
};
class Transport {
public:
virtual void RDMAWriteWithImm(MessageBuffer *msg_buf, uint64_t remote_addr,
uint32_t rkey, uint32_t idx) = 0;
virtual int RecvPushRequest(Message *msg, BufferContext *buffer_ctx,
int meta_len) = 0;
virtual int RecvPullRequest(Message *msg, BufferContext *buffer_ctx,
int meta_len) = 0;
virtual int RecvPushResponse(Message *msg, BufferContext *buffer_ctx,
int meta_len) = 0;
virtual int RecvPullResponse(Message *msg, BufferContext *buffer_ctx,
int meta_len) = 0;
virtual void Send(Message &msg, MessageBuffer *msg_buf,
RemoteTuple remote_tuple) = 0;
virtual void SendPullRequest(Message &msg, MessageBuffer *msg_buf,
RemoteTuple remote_tuple) = 0;
virtual void SendPushRequest(Message &msg, MessageBuffer *msg_buf,
RemoteTuple remote_tuple) = 0;
virtual void SendPushResponse(Message &msg, MessageBuffer *msg_buf,
RemoteTuple remote_tuple) = 0;
virtual void SendPullResponse(Message &msg, MessageBuffer *msg_buf,
RemoteTuple remote_tuple, size_t lkey) = 0;
virtual void SendRendezvousBegin(Message &msg, MessageBuffer *msg_buf) = 0;
virtual void SendRendezvousReply(RendezvousStart *req,
AddressPool<BufferContext> &pool) = 0;
virtual SArray<char> CreateFunctionalSarray(void *value, size_t size) = 0;
}; // class Transport
class RDMATransport : public Transport {
public:
explicit RDMATransport(Endpoint *endpoint, MemoryAllocator *allocator,
Postoffice *postoffice) {
endpoint_ = CHECK_NOTNULL(endpoint);
allocator_ = CHECK_NOTNULL(allocator);
pagesize_ = sysconf(_SC_PAGESIZE);
postoffice_ = postoffice;
is_server_ = postoffice_->is_server();
};
~RDMATransport(){};
virtual void RDMAWriteWithImm(MessageBuffer *msg_buf, uint64_t remote_addr,
uint32_t rkey, uint32_t idx) {
struct ibv_sge sge;
sge.addr = reinterpret_cast<uint64_t>(msg_buf->inline_buf);
sge.length = msg_buf->inline_len;
sge.lkey = allocator_->LocalKey(msg_buf->inline_buf);
struct ibv_send_wr wr, *bad_wr = nullptr;
memset(&wr, 0, sizeof(wr));
wr.wr_id = reinterpret_cast<uint64_t>(msg_buf);
wr.opcode = IBV_WR_RDMA_WRITE_WITH_IMM;
wr.next = nullptr;
wr.imm_data = idx;
wr.send_flags = IBV_SEND_SIGNALED;
wr.sg_list = &sge;
wr.num_sge = 1;
wr.wr.rdma.remote_addr = remote_addr;
wr.wr.rdma.rkey = rkey;
CHECK_EQ(ibv_post_send(endpoint_->cm_id->qp, &wr, &bad_wr), 0)
<< "ibv_post_send failed.";
}
void SendRendezvousBegin(Message &msg, MessageBuffer *msg_buf) {
WRContext *context = nullptr;
endpoint_->free_start_ctx.WaitAndPop(&context);
RendezvousStart *req =
reinterpret_cast<RendezvousStart *>(context->buffer->addr);
req->meta_len = msg_buf->inline_len;
req->origin_addr = reinterpret_cast<uint64_t>(msg_buf);
req->data_num = msg_buf->data.size();
for (size_t i = 0; i < req->data_num; ++i) {
req->data_len[i] = msg.data[i].size();
}
struct ibv_sge sge;
sge.addr = reinterpret_cast<uint64_t>(req);
sge.lkey = context->buffer->lkey;
sge.length = sizeof(RendezvousStart);
struct ibv_send_wr wr, *bad_wr = nullptr;
memset(&wr, 0, sizeof(wr));
wr.wr_id = reinterpret_cast<uint64_t>(context);
wr.opcode = IBV_WR_SEND_WITH_IMM;
wr.next = nullptr;
wr.imm_data = kRendezvousStart;
wr.send_flags = IBV_SEND_SIGNALED;
wr.sg_list = &sge;
wr.num_sge = 1;
CHECK_EQ(ibv_post_send(endpoint_->cm_id->qp, &wr, &bad_wr), 0)
<< strerror(errno);
}
void SendRendezvousReply(RendezvousStart *req,
AddressPool<BufferContext> &addrpool) {
BufferContext *buf_ctx = new BufferContext();
buf_ctx->meta_len = req->meta_len;
buf_ctx->data_num = req->data_num;
size_t data_len = 0;
for (size_t i = 0; i < req->data_num; ++i) {
buf_ctx->data_len[i] = req->data_len[i];
data_len += req->data_len[i];
}
// worker only needs a buffer for receving meta
char *buffer = allocator_->Alloc(
is_server_ ? (align_ceil(req->meta_len, pagesize_) + data_len)
: req->meta_len);
CHECK(buffer);
buf_ctx->buffer = buffer;
WRContext *reply_ctx = nullptr;
endpoint_->free_reply_ctx.WaitAndPop(&reply_ctx);
RendezvousReply *resp =
reinterpret_cast<RendezvousReply *>(reply_ctx->buffer->addr);
resp->addr = reinterpret_cast<uint64_t>(buffer);
resp->rkey = allocator_->RemoteKey(buffer);
resp->origin_addr = req->origin_addr;
resp->idx = addrpool.StoreAddress(buf_ctx);
struct ibv_sge sge;
sge.addr = reinterpret_cast<uint64_t>(resp);
sge.length = sizeof(RendezvousReply);
sge.lkey = reply_ctx->buffer->lkey;
struct ibv_send_wr wr, *bad_wr = nullptr;
memset(&wr, 0, sizeof(wr));
wr.wr_id = reinterpret_cast<uint64_t>(reply_ctx);
wr.opcode = IBV_WR_SEND_WITH_IMM;
wr.next = nullptr;
wr.imm_data = kRendezvousReply;
wr.send_flags = IBV_SEND_SIGNALED;
wr.sg_list = &sge;
wr.num_sge = 1;
CHECK_EQ(ibv_post_send(endpoint_->cm_id->qp, &wr, &bad_wr), 0)
<< "ibv_post_send failed.";
}
void Send(Message &msg, MessageBuffer *msg_buf, RemoteTuple remote_tuple) {
auto raddr = std::get<0>(remote_tuple);
auto rkey = std::get<1>(remote_tuple);
auto idx = std::get<2>(remote_tuple);
RDMAWriteWithImm(msg_buf, raddr, rkey, idx);
}
void SendPushRequest(Message &msg, MessageBuffer *msg_buf,
RemoteTuple remote_tuple) {
CHECK_EQ(msg_buf->mrs.size(), 1);
auto raddr = std::get<0>(remote_tuple);
auto rkey = std::get<1>(remote_tuple);
auto idx = std::get<2>(remote_tuple);
// push request, split the meta and data into two writes
// further, it does not send keys and lens since these meta already carries
// these info
struct ibv_sge my_sge;
my_sge.addr = reinterpret_cast<uint64_t>(msg_buf->mrs[0].first->addr);
// support variable data length
CHECK(msg.data.size() == 3);
// the data size sent this time must be no larger than the one we registered
// the first time
CHECK(msg.data[1].size() <= msg_buf->mrs[0].second);
my_sge.length = msg.data[1].size();
my_sge.lkey = msg_buf->mrs[0].first->lkey;
// this rdma-write will not trigger any signal both remotely and locally
struct ibv_send_wr wr, *bad_wr = nullptr;
memset(&wr, 0, sizeof(wr));
wr.wr_id = 0;
wr.opcode = IBV_WR_RDMA_WRITE;
wr.next = nullptr;
wr.sg_list = &my_sge;
wr.num_sge = 1;
wr.wr.rdma.rkey = rkey;
// write to the next page-aligned address (remote_addr should already be
// aligned)
wr.wr.rdma.remote_addr = raddr + align_ceil(msg_buf->inline_len, pagesize_);
CHECK_EQ(ibv_post_send(endpoint_->cm_id->qp, &wr, &bad_wr), 0)
<< "ibv_post_send failed.";
RDMAWriteWithImm(msg_buf, raddr, rkey, idx);
}
void SendPullRequest(Message &msg, MessageBuffer *msg_buf,
RemoteTuple remote_tuple) {
CHECK_EQ(msg_buf->mrs.size(), 0);
Send(msg, msg_buf, remote_tuple);
}
virtual void SendPushResponse(Message &msg, MessageBuffer *msg_buf,
RemoteTuple remote_tuple) {
CHECK_EQ(msg_buf->mrs.size(), 0);
Send(msg, msg_buf, remote_tuple);
}
virtual void SendPullResponse(Message &msg, MessageBuffer *msg_buf,
RemoteTuple remote_tuple, size_t lkey) {
CHECK_EQ(msg_buf->mrs.size(), 0);
auto raddr = msg.meta.addr;
auto rkey = msg.meta.option;
auto len = msg.meta.val_len;
CHECK_EQ((size_t)msg.meta.val_len, msg_buf->data[1].size());
struct ibv_sge sge;
sge.addr = reinterpret_cast<uint64_t>(msg_buf->data[1].data());
sge.length = len;
sge.lkey = lkey;
// this rdma-write will not trigger any signal both remotely and locally
struct ibv_send_wr wr, *bad_wr = nullptr;
memset(&wr, 0, sizeof(wr));
wr.wr_id = reinterpret_cast<uint64_t>(raddr);
wr.opcode = IBV_WR_RDMA_WRITE;
wr.next = nullptr;
wr.sg_list = &sge;
wr.num_sge = 1;
wr.wr.rdma.remote_addr = raddr;
wr.wr.rdma.rkey = rkey;
CHECK_EQ(ibv_post_send(endpoint_->cm_id->qp, &wr, &bad_wr), 0)
<< "ibv_post_send failed.";
// after write keys/vals/lens (no imm), write the meta (with imm)
Send(msg, msg_buf, remote_tuple);
}
virtual int RecvPushResponse(Message *msg, BufferContext *buffer_ctx,
int meta_len) {
CHECK_EQ(buffer_ctx->data_num, 0);
return 0;
}
virtual int RecvPullRequest(Message *msg, BufferContext *buffer_ctx,
int meta_len) {
SArray<char> keys = CreateFunctionalSarray(&msg->meta.key, sizeof(Key));
SArray<char> vals; // add an empty sarray to pass kvapp check
msg->data.push_back(keys);
msg->data.push_back(vals);
return keys.size() + vals.size();
}
virtual int RecvPushRequest(Message *msg, BufferContext *buffer_ctx,
int meta_len) {
CHECK(msg->meta.push && msg->meta.request);
CHECK_EQ(buffer_ctx->data_num, 3);
char *cur = buffer_ctx->buffer + align_ceil((size_t)meta_len, pagesize_);
SArray<char> keys = CreateFunctionalSarray(&msg->meta.key, sizeof(Key));
uint32_t len = msg->meta.val_len;
SArray<char> vals;
vals.reset(cur, len, [](void *) {}); // no need to delete
SArray<char> lens = CreateFunctionalSarray(&msg->meta.val_len, sizeof(int));
msg->data.push_back(keys);
msg->data.push_back(vals);
msg->data.push_back(lens);
return keys.size() + vals.size() + lens.size();
}
virtual int RecvPullResponse(Message *msg, BufferContext *buffer_ctx,
int meta_len) {
SArray<char> keys = CreateFunctionalSarray(&msg->meta.key, sizeof(Key));
SArray<char> vals;
auto addr = msg->meta.addr;
vals.reset(reinterpret_cast<char *>(addr), msg->meta.val_len,
[](void *) {});
SArray<char> lens = CreateFunctionalSarray(&msg->meta.val_len, sizeof(int));
msg->data.push_back(keys);
msg->data.push_back(vals);
msg->data.push_back(lens);
return keys.size() + vals.size() + lens.size();
}
SArray<char> CreateFunctionalSarray(void *value, size_t size) {
SArray<char> sarr;
void *p = malloc(size);
memcpy(p, value, size);
sarr.reset((char *)p, size, [p](void *) { free(p); });
return sarr;
}
protected:
size_t pagesize_ = 4096;
Endpoint *endpoint_;
MemoryAllocator *allocator_;
bool is_server_;
Postoffice *postoffice_;
}; // class Transport
class IPCTransport : public RDMATransport {
public:
explicit IPCTransport(Endpoint *endpoint, MemoryAllocator *allocator,
Postoffice *postoffice)
: RDMATransport(endpoint, allocator, postoffice) {
auto val = Environment::Get()->find("BYTEPS_IPC_COPY_NUM_THREADS");
ipc_copy_nthreads_ = val ? atoi(val) : 4;
for (int i = 0; i < ipc_copy_nthreads_; ++i) {
auto q = new ThreadsafeQueue<AsyncCopy>;
async_copy_queue_.push_back(q);
}
for (int i = 0; i < ipc_copy_nthreads_; ++i) {
auto t = new std::thread(&IPCTransport::AsyncCopyThread, this, i);
ipc_copy_thread_list_.push_back(t);
}
val = Environment::Get()->find("BYTEPS_PARTITION_BYTES");
byteps_partition_bytes_ = val ? atoi(val) : 4096000;
val = Environment::Get()->find("BYTEPS_ENCODING_SCHEME_VERSION");
encoding_scheme_version_ = val ? atoi(val) : 0;
val = Environment::Get()->find("BYTEPS_LOCAL_SIZE");
auto byteps_local_size = val ? atoi(val) : 8;
byteps_partition_bytes_ = RoundUp(
byteps_partition_bytes_, byteps_local_size * sysconf(_SC_PAGESIZE));
val = Environment::Get()->find("BYTEPS_IPC_ENABLE_ASYNC_COPY");
enable_async_copy_ = val ? atoi(val) : 1; // default enabled
if (!enable_async_copy_)
LOG(INFO)
<< "Async copy has been disabled, this could affect the performance";
val = Environment::Get()->find("BYTEPS_PCIE_SWITCH_SIZE");
auto byteps_nccl_pcie_size = val ? atoi(val) : 8;
if (byteps_local_size % byteps_nccl_pcie_size != 0) {
// local_size < pcie_size or unbalance PCIe switches
byteps_nccl_pcie_size = byteps_local_size;
}
// ensure this name corresponds with that in
// BytePSSharedMemory::openPcieSharedMemory()
if (byteps_local_size > byteps_nccl_pcie_size) {
// cross pcie switch, use the last pcie cpu buffer
auto byteps_pcie_num = byteps_local_size / byteps_nccl_pcie_size;
shm_prefix_ =
kShmPciePrefix + std::to_string(byteps_pcie_num - 1) + "_Shm_";
} else {
shm_prefix_ = kShmPrefix;
}
val = Environment::Get()->find("BYTEPS_JOB_ID");
std::string _job_id = val ? std::string(val) : "0";
shm_prefix_ = shm_prefix_ + _job_id + "_";
};
~IPCTransport() {
for (size_t i = 0; i < ipc_copy_thread_list_.size(); ++i) {
AsyncCopy m;
m.shutdown = true;
async_copy_queue_[i]->Push(m);
ipc_copy_thread_list_[i]->join();
}
}
void SendPushRequest(Message &msg, MessageBuffer *msg_buf,
RemoteTuple remote_tuple) {
Send(msg, msg_buf, remote_tuple);
}
void SendPullResponse(Message &msg, MessageBuffer *msg_buf,
RemoteTuple remote_tuple, size_t lkey) {
auto addr = (void *)CHECK_NOTNULL(msg.data[1].data());
void *shm_addr = CHECK_NOTNULL(GetSharedMemory(shm_prefix_, msg.meta.key));
if (enable_async_copy_) {
// async copy with a simple load-balancing strategy
AsyncCopy m = {msg_buf, remote_tuple, shm_addr,
addr, msg.meta.val_len, false};
auto cnt = cpy_counter_.fetch_add(1);
async_copy_queue_[cnt % ipc_copy_nthreads_]->Push(m);
} else {
// synchronous copy
memcpy(shm_addr, addr, msg.meta.val_len);
Send(msg, msg_buf, remote_tuple);
}
}
int RecvPushRequest(Message *msg, BufferContext *buffer_ctx, int meta_len) {
// get data message from local shared memory
auto key = msg->meta.key;
auto len = msg->meta.val_len;
SArray<char> keys = CreateFunctionalSarray(&msg->meta.key, sizeof(Key));
SArray<char> vals;
void *addr = GetSharedMemory(shm_prefix_, key);
vals.reset(reinterpret_cast<char *>(addr), len, [](void *) {});
SArray<char> lens = CreateFunctionalSarray(&msg->meta.val_len, sizeof(int));
msg->data.push_back(keys);
msg->data.push_back(vals);
msg->data.push_back(lens);
return keys.size() + vals.size() + lens.size();
}
private:
struct AsyncCopy {
MessageBuffer *msg_buf;
RemoteTuple remote_tuple;
void *dst;
void *src;
int len;
bool shutdown;
};
void AsyncCopyThread(int i) {
auto &q = async_copy_queue_[i];
while (true) {
AsyncCopy m;
q->WaitAndPop(&m);
if (m.shutdown) break;
if (m.len == 0) continue;
// TODO: use parallel copy
CHECK(m.dst);
CHECK(m.src);
memcpy(m.dst, m.src, m.len);
auto raddr = std::get<0>(m.remote_tuple);
auto rkey = std::get<1>(m.remote_tuple);
auto idx = std::get<2>(m.remote_tuple);
RDMAWriteWithImm(m.msg_buf, raddr, rkey, idx);
}
}
void *GetSharedMemory(const std::string &prefix, uint64_t key) {
std::lock_guard<std::mutex> lock(shm_mu_);
auto worker_key = DecodeWorkerKey(key);
auto seq_num = worker_key % (1 << 16);
// Total key space is [0, 2^64 - 1]
// It will be divided to N PS servers, for now we assume N <= 2^16
// Then we have 2^48 key space left.
// Encoding scheme version 0:
// Then we have 2^48 key space left (top 16 bits for different servers)
// MXNet server has a bug dealing with keys larger than 2^32
// Below we support up to 2^16 tensors, and up to 2^16 partitions per
// tensor
// Encoding scheme version 1:
// Top 16 bits out of the 48 bits encodes the sender rank
// Mid 16 bits out of the 48 bits encodes the tensor id
// The next 6 bits encodes request types (pushpull, send, etc)
// The last 10 bits encodes the partition id
// Therefore, we support up to 2^16 tensors, and up to 2^10 partitions per
// tensor
if (encoding_scheme_version_ == 1) {
seq_num = worker_key % (1 << 10);
}
auto base_key = worker_key - seq_num;
uint64_t offset = byteps_partition_bytes_ * seq_num;
if (key_shm_addr_.find(base_key) != key_shm_addr_.end()) {
return (void *)((char *)key_shm_addr_[base_key] + offset);
}
std::string shm_name(prefix);
std::stringstream stream;
stream << std::hex << base_key;
shm_name += stream.str();
int shm_fd = shm_open(shm_name.c_str(), O_RDWR, 0666);
CHECK_GE(shm_fd, 0) << "shm_open failed for " << shm_name << ", "
<< strerror(errno);
struct stat sb;
CHECK_EQ(0, fstat(shm_fd, &sb)) << strerror(errno);
auto total_shm_size = sb.st_size;
void *base_ptr =
mmap(0, total_shm_size, PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, 0);
CHECK_NE(base_ptr, (void *)-1) << strerror(errno);
key_shm_addr_[base_key] = base_ptr;
PS_VLOG(1) << "open Shared Memory: " << shm_name << " offset=" << offset
<< " (in bytes) size=" << total_shm_size;
return (void *)((char *)key_shm_addr_[base_key] + offset);
}
int ipc_copy_nthreads_;
std::vector<std::thread *> ipc_copy_thread_list_;
std::vector<ThreadsafeQueue<AsyncCopy> *> async_copy_queue_;
std::atomic<unsigned long long> cpy_counter_{0};
int byteps_partition_bytes_ = 4096000;
std::string shm_prefix_;
std::mutex shm_mu_;
std::unordered_map<uint64_t, void *> key_shm_addr_;
bool enable_async_copy_;
int encoding_scheme_version_ = 0;
}; // class IPCTransport
}; // namespace ps
#endif // DMLC_USE_RDMA
#endif // PS_RDMA_VAN_H_