aea866c12c
Previously we used a single port to implement the RPC. This was sufficient for single threaded tests but can potentially cause deadlocks when using multiple threads. The reason for this is that GPUs make no forward progress guarantees. Therefore one group of threads waiting on another group of threads can spin forever because there is no guarantee that the other threads will continue executing. The typical workaround for this is to allocate enough memory that a sufficiently large number of work groups can make progress. As long as this number is somewhat close to the amount of total concurrency we can obtain reliable execution around a shared resource. This patch enables using multiple ports by widening the arrays to a predetermined size and indexes into them. Empty ports are currently obtained via a trivial linker scan. This should be imporoved in the future for performance reasons. Portions of D148191 were applied to achieve parallel support. Depends on D149581 Reviewed By: JonChesterfield Differential Revision: https://reviews.llvm.org/D149598
70 lines
2.0 KiB
C++
70 lines
2.0 KiB
C++
//===-- Generic RPC server interface --------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_UTILS_GPU_LOADER_RPC_H
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#define LLVM_LIBC_UTILS_GPU_LOADER_RPC_H
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#include <cstdint>
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#include <cstdio>
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#include <cstdlib>
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#include <cstring>
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#include <stddef.h>
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#include "src/__support/RPC/rpc.h"
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static __llvm_libc::rpc::Server server;
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static __llvm_libc::cpp::Atomic<uint32_t>
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lock[__llvm_libc::rpc::default_port_count] = {0};
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/// Queries the RPC client at least once and performs server-side work if there
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/// are any active requests.
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void handle_server() {
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// Continue servicing the client until there is no work left and we return.
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for (;;) {
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auto port = server.try_open();
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if (!port)
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return;
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switch (port->get_opcode()) {
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case __llvm_libc::rpc::Opcode::PRINT_TO_STDERR: {
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uint64_t str_size[__llvm_libc::rpc::MAX_LANE_SIZE] = {0};
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char *strs[__llvm_libc::rpc::MAX_LANE_SIZE] = {nullptr};
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port->recv_n([&](uint64_t size, uint32_t id) {
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str_size[id] = size;
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strs[id] = new char[size];
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return strs[id];
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});
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for (uint64_t i = 0; i < __llvm_libc::rpc::MAX_LANE_SIZE; ++i) {
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if (strs[i]) {
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fwrite(strs[i], str_size[i], 1, stderr);
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delete[] strs[i];
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}
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}
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break;
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}
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case __llvm_libc::rpc::Opcode::EXIT: {
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port->recv([](__llvm_libc::rpc::Buffer *buffer) {
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exit(reinterpret_cast<uint32_t *>(buffer->data)[0]);
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});
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break;
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}
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case __llvm_libc::rpc::Opcode::TEST_INCREMENT: {
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port->recv_and_send([](__llvm_libc::rpc::Buffer *buffer) {
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reinterpret_cast<uint64_t *>(buffer->data)[0] += 1;
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});
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break;
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}
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default:
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port->recv([](__llvm_libc::rpc::Buffer *buffer) {});
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}
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port->close();
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}
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}
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#endif
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