[libc-commits] [libc] ae30ae2 - [libc][NFC] Add some missing comments to the RPC implementation
Joseph Huber via libc-commits
libc-commits at lists.llvm.org
Mon Mar 20 07:30:33 PDT 2023
Author: Joseph Huber
Date: 2023-03-20T09:30:12-05:00
New Revision: ae30ae23aa4026bbc05c1de89a8d69b3cc2d9158
URL: https://github.com/llvm/llvm-project/commit/ae30ae23aa4026bbc05c1de89a8d69b3cc2d9158
DIFF: https://github.com/llvm/llvm-project/commit/ae30ae23aa4026bbc05c1de89a8d69b3cc2d9158.diff
LOG: [libc][NFC] Add some missing comments to the RPC implementation
Summary:
These comments were accidentally dropped from the committed version. Add
them back in.
Added:
Modified:
libc/src/__support/OSUtil/gpu/io.cpp
libc/src/__support/OSUtil/gpu/quick_exit.cpp
libc/src/__support/RPC/rpc.h
libc/utils/gpu/loader/amdgpu/Loader.cpp
Removed:
################################################################################
diff --git a/libc/src/__support/OSUtil/gpu/io.cpp b/libc/src/__support/OSUtil/gpu/io.cpp
index 75ac83ac6909c..dcc3bf76ec068 100644
--- a/libc/src/__support/OSUtil/gpu/io.cpp
+++ b/libc/src/__support/OSUtil/gpu/io.cpp
@@ -16,14 +16,15 @@ namespace __llvm_libc {
void write_to_stderr(const char *msg) {
uint64_t length = internal::string_length(msg) + 1;
uint64_t buffer_len = sizeof(rpc::Buffer) - sizeof(uint64_t);
- for (uint64_t i = 0; i < length; i += buffer_len)
+ for (uint64_t i = 0; i < length; i += buffer_len) {
rpc::client.run(
[&](rpc::Buffer *buffer) {
buffer->data[0] = rpc::Opcode::PRINT_TO_STDERR;
inline_memcpy(reinterpret_cast<char *>(&buffer->data[1]), &msg[i],
(length > buffer_len ? buffer_len : length));
},
- [](rpc::Buffer *) {});
+ [](rpc::Buffer *) { /* void */ });
+ }
}
} // namespace __llvm_libc
diff --git a/libc/src/__support/OSUtil/gpu/quick_exit.cpp b/libc/src/__support/OSUtil/gpu/quick_exit.cpp
index 9be709552dc5c..56f0427c8d81b 100644
--- a/libc/src/__support/OSUtil/gpu/quick_exit.cpp
+++ b/libc/src/__support/OSUtil/gpu/quick_exit.cpp
@@ -24,7 +24,7 @@ void quick_exit(int status) {
buffer->data[0] = rpc::Opcode::EXIT;
buffer->data[1] = status;
},
- [](rpc::Buffer *) {});
+ [](rpc::Buffer *) { /* void */ });
#if defined(LIBC_TARGET_ARCH_IS_NVPTX)
asm("exit" ::: "memory");
diff --git a/libc/src/__support/RPC/rpc.h b/libc/src/__support/RPC/rpc.h
index c3df09e3f5db2..d536de49bf5ff 100644
--- a/libc/src/__support/RPC/rpc.h
+++ b/libc/src/__support/RPC/rpc.h
@@ -5,6 +5,15 @@
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
+//
+// This file implements a remote procedure call mechanism to communicate between
+// heterogeneous devices that can share an address space atomically. We provide
+// a client and a server to facilitate the remote call. The client makes request
+// to the server using a shared communication channel. We use separate atomic
+// signals to indicate which side, the client or the server is in ownership of
+// the buffer.
+//
+//===----------------------------------------------------------------------===//
#ifndef LLVM_LIBC_SRC_SUPPORT_RPC_RPC_H
#define LLVM_LIBC_SRC_SUPPORT_RPC_RPC_H
@@ -55,7 +64,7 @@ struct Client : public Process {
/// The RPC server used to respond to the client.
struct Server : public Process {
- template <typename W, typename C> bool run(W work, C clean);
+ template <typename W, typename C> bool handle(W work, C clean);
};
/// Run the RPC client protocol to communicate with the server. We perform the
@@ -68,27 +77,27 @@ template <typename F, typename U> void Client::run(F fill, U use) {
bool in = inbox->load(cpp::MemoryOrder::RELAXED);
bool out = outbox->load(cpp::MemoryOrder::RELAXED);
atomic_thread_fence(cpp::MemoryOrder::ACQUIRE);
- // Write to buffer then to the outbox.
+ // Apply the \p fill to the buffer and signal the server.
if (!in & !out) {
fill(buffer);
atomic_thread_fence(cpp::MemoryOrder::RELEASE);
outbox->store(1, cpp::MemoryOrder::RELEASE);
out = 1;
}
- // Wait for the result from the server.
+ // Wait for the server to work on the buffer and respond.
if (!in & out) {
while (!in)
in = inbox->load(cpp::MemoryOrder::RELAXED);
atomic_thread_fence(cpp::MemoryOrder::ACQUIRE);
}
- // Read from the buffer and then write to outbox.
+ // Apply \p use to the buffer and signal the server.
if (in & out) {
use(buffer);
atomic_thread_fence(cpp::MemoryOrder::RELEASE);
outbox->store(0, cpp::MemoryOrder::RELEASE);
out = 0;
}
- // Wait for server to complete the communication.
+ // Wait for the server to signal the end of the protocol.
if (in & !out) {
while (in)
in = inbox->load(cpp::MemoryOrder::RELAXED);
@@ -103,27 +112,27 @@ template <typename F, typename U> void Client::run(F fill, U use) {
/// - Apply \p work to the shared buffer and write 1 to the outbox.
/// - Wait until the inbox is 0.
/// - Apply \p clean to the shared buffer and write 0 to the outbox.
-template <typename W, typename C> bool Server::run(W work, C clean) {
+template <typename W, typename C> bool Server::handle(W work, C clean) {
bool in = inbox->load(cpp::MemoryOrder::RELAXED);
bool out = outbox->load(cpp::MemoryOrder::RELAXED);
atomic_thread_fence(cpp::MemoryOrder::ACQUIRE);
- // No work to do, exit.
+ // There is no work to do, exit early.
if (!in & !out)
return false;
- // Do work then write to the outbox.
+ // Apply \p work to the buffer and signal the client.
if (in & !out) {
work(buffer);
atomic_thread_fence(cpp::MemoryOrder::RELEASE);
outbox->store(1, cpp::MemoryOrder::RELEASE);
out = 1;
}
- // Wait for the client to read the result.
+ // Wait for the client to use the buffer and respond.
if (in & out) {
while (in)
in = inbox->load(cpp::MemoryOrder::RELAXED);
atomic_thread_fence(cpp::MemoryOrder::ACQUIRE);
}
- // Clean up the buffer and signal the client.
+ // Clean up the buffer and signal the end of the protocol.
if (!in & out) {
clean(buffer);
atomic_thread_fence(cpp::MemoryOrder::RELEASE);
diff --git a/libc/utils/gpu/loader/amdgpu/Loader.cpp b/libc/utils/gpu/loader/amdgpu/Loader.cpp
index 3136dc2509790..0d631e98aae43 100644
--- a/libc/utils/gpu/loader/amdgpu/Loader.cpp
+++ b/libc/utils/gpu/loader/amdgpu/Loader.cpp
@@ -43,7 +43,7 @@ static __llvm_libc::rpc::Server server;
/// Queries the RPC client at least once and performs server-side work if there
/// are any active requests.
void handle_server() {
- while (server.run(
+ while (server.handle(
[&](__llvm_libc::rpc::Buffer *buffer) {
switch (static_cast<__llvm_libc::rpc::Opcode>(buffer->data[0])) {
case __llvm_libc::rpc::Opcode::PRINT_TO_STDERR: {
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