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[GGML][RPC] Support for models with non-512-aligned tensors over RPC. (
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…#11047)

* Added init tensor calling code

* Added get_alloc_size forwarding

* Cleaned up and improved type/error handling.

* fix: remove trailing whitespaces.

* Cleanup and use GGML error logging functions.

* Handle potentially dangerous edge cases.

* Apply suggestions from code review

Co-authored-by: Diego Devesa <[email protected]>

---------

Co-authored-by: Diego Devesa <[email protected]>
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matt23654 and slaren authored Jan 4, 2025
1 parent 46be942 commit f922a9c
Showing 1 changed file with 134 additions and 6 deletions.
140 changes: 134 additions & 6 deletions ggml/src/ggml-rpc/ggml-rpc.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -93,9 +93,23 @@ enum rpc_cmd {
RPC_CMD_COPY_TENSOR,
RPC_CMD_GRAPH_COMPUTE,
RPC_CMD_GET_DEVICE_MEMORY,
RPC_CMD_INIT_TENSOR,
RPC_CMD_GET_ALLOC_SIZE,
RPC_CMD_COUNT,
};

struct rpc_msg_get_alloc_size_req {
rpc_tensor tensor;
};

struct rpc_msg_get_alloc_size_rsp {
uint64_t alloc_size;
};

struct rpc_msg_init_tensor_req {
rpc_tensor tensor;
};

struct rpc_msg_alloc_buffer_req {
uint64_t size;
};
Expand Down Expand Up @@ -461,10 +475,18 @@ static rpc_tensor serialize_tensor(const ggml_tensor * tensor) {
}

static void ggml_backend_rpc_buffer_init_tensor(ggml_backend_buffer_t buffer, ggml_tensor * tensor) {
UNUSED(buffer);
if (ggml_is_quantized(tensor->type)) {
// TODO: this check is due to MATRIX_ROW_PADDING in CUDA and should be generalized
GGML_ASSERT(tensor->ne[0] % 512 == 0 && "unsupported quantized tensor");
ggml_backend_rpc_buffer_context * ctx = (ggml_backend_rpc_buffer_context *)buffer->context;

// CUDA backend on the server pads everything to 512 due to CUDA limitations.
// Due to bandwidth constraints, we only call the server init tensor functions if necessary.
// In particular, only quantized tensors need padding
if (ggml_is_quantized(tensor->type) && (tensor->ne[0] % 512 != 0) && (tensor->view_src == nullptr)) {
rpc_msg_init_tensor_req request;

request.tensor = serialize_tensor(tensor);

bool status = send_rpc_cmd(ctx->sock, RPC_CMD_INIT_TENSOR, &request, sizeof(request), nullptr, 0);
GGML_ASSERT(status);
}
}

Expand Down Expand Up @@ -577,8 +599,23 @@ static size_t ggml_backend_rpc_get_max_size(ggml_backend_buffer_type_t buft) {
}

static size_t ggml_backend_rpc_buffer_type_get_alloc_size(ggml_backend_buffer_type_t buft, const ggml_tensor * tensor) {
UNUSED(buft);
return ggml_nbytes(tensor);
// See comments in init_tensor.
if (ggml_is_quantized(tensor->type) && (tensor->ne[0] % 512 != 0) && (tensor->view_src == nullptr)) {
ggml_backend_rpc_buffer_type_context * buft_ctx = (ggml_backend_rpc_buffer_type_context *)buft->context;
auto sock = get_socket(buft_ctx->endpoint);

rpc_msg_get_alloc_size_req request;

request.tensor = serialize_tensor(tensor);

rpc_msg_get_alloc_size_rsp response;
bool status = send_rpc_cmd(sock, RPC_CMD_GET_ALLOC_SIZE, &request, sizeof(request), &response, sizeof(response));
GGML_ASSERT(status);

return response.alloc_size;
} else {
return ggml_nbytes(tensor);
}
}

static ggml_backend_buffer_type_i ggml_backend_rpc_buffer_type_interface = {
Expand Down Expand Up @@ -757,6 +794,8 @@ class rpc_server {
bool get_tensor(const rpc_msg_get_tensor_req & request, std::vector<uint8_t> & response);
bool copy_tensor(const rpc_msg_copy_tensor_req & request, rpc_msg_copy_tensor_rsp & response);
bool graph_compute(const std::vector<uint8_t> & input, rpc_msg_graph_compute_rsp & response);
bool init_tensor(const rpc_msg_init_tensor_req & request);
bool get_alloc_size(const rpc_msg_get_alloc_size_req & request, rpc_msg_get_alloc_size_rsp & response);

private:
ggml_tensor * deserialize_tensor(struct ggml_context * ctx, const rpc_tensor * tensor);
Expand All @@ -770,6 +809,36 @@ class rpc_server {
std::unordered_set<ggml_backend_buffer_t> buffers;
};

bool rpc_server::get_alloc_size(const rpc_msg_get_alloc_size_req & request, rpc_msg_get_alloc_size_rsp & response) {
ggml_backend_buffer_type_t buft;
struct ggml_init_params params {
/*.mem_size =*/ ggml_tensor_overhead(),
/*.mem_buffer =*/ NULL,
/*.no_alloc =*/ true,
};

struct ggml_context * ctx = ggml_init(params);
ggml_tensor * tensor = deserialize_tensor(ctx, &request.tensor);

if (tensor == nullptr) {
GGML_LOG_ERROR("Null tensor pointer passed to server get_alloc_size function.\n");
ggml_free(ctx);
return false;
}

if (tensor->buffer == nullptr) {
//No buffer allocated.
buft = ggml_backend_get_default_buffer_type(backend);
} else {
buft = tensor->buffer->buft;
}

response.alloc_size = ggml_backend_buft_get_alloc_size(buft,tensor);

ggml_free(ctx);
return true;
}

void rpc_server::alloc_buffer(const rpc_msg_alloc_buffer_req & request, rpc_msg_alloc_buffer_rsp & response) {
ggml_backend_buffer_type_t buft = ggml_backend_get_default_buffer_type(backend);
ggml_backend_buffer_t buffer = ggml_backend_buft_alloc_buffer(buft, request.size);
Expand Down Expand Up @@ -905,6 +974,40 @@ bool rpc_server::set_tensor(const std::vector<uint8_t> & input) {
return true;
}

bool rpc_server::init_tensor(const rpc_msg_init_tensor_req & request) {
struct ggml_init_params params {
/*.mem_size =*/ ggml_tensor_overhead(),
/*.mem_buffer =*/ NULL,
/*.no_alloc =*/ true,
};
struct ggml_context * ctx = ggml_init(params);
ggml_tensor * tensor = deserialize_tensor(ctx, &request.tensor);
if (tensor == nullptr) {
GGML_LOG_ERROR("Null tensor pointer passed to server init_tensor function.\n");
ggml_free(ctx);
return false;
}

// Call the backend's buffer_init_tensor function
ggml_backend_buffer_t buffer = tensor->buffer;
if (buffer && buffer->iface.init_tensor) {
buffer->iface.init_tensor(buffer, tensor);
} else {
GGML_LOG_ERROR("Null buffer for tensor passed to init_tensor function\n");
}

if (tensor->extra != nullptr) {
// This pointer can either be passed around client/server, or probably better stored server-side and kept track of.
// Currently unimplemented.
GGML_LOG_ERROR("tensor->extra populated by the backend, this is currently unsupported.\n");
ggml_free(ctx);
return false;
}

ggml_free(ctx);
return true;
}

bool rpc_server::get_tensor(const rpc_msg_get_tensor_req & request, std::vector<uint8_t> & response) {
struct ggml_init_params params {
/*.mem_size =*/ ggml_tensor_overhead(),
Expand Down Expand Up @@ -1058,6 +1161,18 @@ static void rpc_serve_client(ggml_backend_t backend, sockfd_t sockfd, size_t fre
}
break;
}
case RPC_CMD_GET_ALLOC_SIZE: {
rpc_msg_get_alloc_size_req request;
if (!recv_msg(sockfd, &request, sizeof(request))) {
return;
}
rpc_msg_get_alloc_size_rsp response;
server.get_alloc_size(request, response);
if (!send_msg(sockfd, &response, sizeof(response))) {
return;
}
break;
}
case RPC_CMD_GET_ALIGNMENT: {
if (!recv_msg(sockfd, nullptr, 0)) {
return;
Expand Down Expand Up @@ -1133,6 +1248,19 @@ static void rpc_serve_client(ggml_backend_t backend, sockfd_t sockfd, size_t fre
}
break;
}
case RPC_CMD_INIT_TENSOR: {
rpc_msg_init_tensor_req request;
if (!recv_msg(sockfd, &request,sizeof(request))) {
return;
}
if (!server.init_tensor(request)) {
return;
}
if (!send_msg(sockfd, nullptr, 0)) {
return;
}
break;
}
case RPC_CMD_GET_TENSOR: {
rpc_msg_get_tensor_req request;
if (!recv_msg(sockfd, &request, sizeof(request))) {
Expand Down

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