fix(linux): enable lowlatency mode for AMD (#3088)

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();