fix(linux): enable lowlatency mode for AMD

src/platform/common.h

@@ -612,6 +612,23 @@ namespace platf {
   void
   restart();
 
+  /**
+   * @brief Set an environment variable.
+   * @param name The name of the environment variable.
+   * @param value The value to set the environment variable to.
+   * @return 0 on success, non-zero on failure.
+   */
+  int
+  set_env(const std::string &name, const std::string &value);
+
+  /**
+   * @brief Unset an environment variable.
+   * @param name The name of the environment variable.
+   * @return 0 on success, non-zero on failure.
+   */
+  int
+  unset_env(const std::string &name);
+
   struct buffer_descriptor_t {
     const char *buffer;
     size_t size;

src/platform/linux/misc.cpp

@@ -326,6 +326,16 @@ namespace platf {
     lifetime::exit_sunshine(0, true);
   }
 
+  int
+  set_env(const std::string &name, const std::string &value) {
+    return setenv(name.c_str(), value.c_str(), 1);
+  }
+
+  int
+  unset_env(const std::string &name) {
+    return unsetenv(name.c_str());
+  }
+
   bool
   request_process_group_exit(std::uintptr_t native_handle) {
     if (kill(-((pid_t) native_handle), SIGTERM) == 0 || errno == ESRCH) {
@@ -913,6 +923,10 @@ namespace platf {
 
   std::unique_ptr<deinit_t>
   init() {
+    // enable low latency mode for AMD
+    // https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30039
+    set_env("AMD_DEBUG", "lowlatency");
+
     // These are allowed to fail.
     gbm::init();
 

src/platform/macos/misc.mm

@@ -253,6 +253,16 @@
     lifetime::exit_sunshine(0, true);
   }
 
+  int
+  set_env(const std::string &name, const std::string &value) {
+    return setenv(name.c_str(), value.c_str(), 1);
+  }
+
+  int
+  unset_env(const std::string &name) {
+    return unsetenv(name.c_str());
+  }
+
   bool
   request_process_group_exit(std::uintptr_t native_handle) {
     if (killpg((pid_t) native_handle, SIGTERM) == 0 || errno == ESRCH) {

src/platform/windows/misc.cpp

@@ -1313,6 +1313,16 @@ namespace platf {
     lifetime::exit_sunshine(0, true);
   }
 
+  int
+  set_env(const std::string &name, const std::string &value) {
+    return _putenv_s(name.c_str(), value.c_str());
+  }
+
+  int
+  unset_env(const std::string &name) {
+    return _putenv_s(name.c_str(), "");
+  }
+
   struct enum_wnd_context_t {
     std::set<DWORD> process_ids;
     bool requested_exit;

tests/unit/platform/test_common.cpp

@@ -0,0 +1,39 @@
+/**
+ * @file tests/unit/platform/test_common.cpp
+ * @brief Test src/platform/common.*.
+ */
+#include <src/platform/common.h>
+
+#include "../../tests_common.h"
+
+struct SetEnvTest: ::testing::TestWithParam<std::tuple<std::string, std::string, int>> {
+protected:
+  void
+  TearDown() override {
+    // Clean up environment variable after each test
+    const auto &[name, value, expected] = GetParam();
+    platf::unset_env(name);
+  }
+};
+
+TEST_P(SetEnvTest, HandlesVariousInputs) {
+  const auto &[name, value, expected] = GetParam();
+  platf::set_env(name, value);
+
+  const char *env_value = std::getenv(name.c_str());
+  if (expected == 0 && !value.empty()) {
+    ASSERT_NE(env_value, nullptr);
+    ASSERT_EQ(std::string(env_value), value);
+  }
+  else {
+    ASSERT_EQ(env_value, nullptr);
+  }
+}
+
+INSTANTIATE_TEST_SUITE_P(
+  SetEnvTests,
+  SetEnvTest,
+  ::testing::Values(
+    std::make_tuple("SUNSHINE_UNIT_TEST_ENV_VAR", "test_value", 0),
+    std::make_tuple("", "test_value", -1),
+    std::make_tuple("SUNSHINE_UNIT_TEST_ENV_VAR", "", 0)));