Pin the scene threads to CPUs

demo/magicleap/Cargo.toml

@@ -19,9 +19,6 @@ crate-type = ["staticlib"]
 [features]
 mocked = ["glutin"]
 
-[profile.release]
-debug = true
-
 [dependencies.pathfinder_demo]
 path = "../common"
 

demo/magicleap/src/lib.rs

@@ -38,7 +38,7 @@ pub extern "C" fn magicleap_pathfinder_demo(egl_display: EGLDisplay, egl_context
     options.ui = false;
     options.background = Background::None;
     options.mode = Mode::VR;
-    options.jobs = Some(2);
+    options.jobs = Some(3);
     options.pipeline = 0;
 
     let mut app = DemoApp::new(window, window_size, options);

demo/magicleap/src/magicleap.rs

@@ -62,6 +62,8 @@ use pathfinder_gpu::resources::FilesystemResourceLoader;
 use pathfinder_gpu::resources::ResourceLoader;
 use pathfinder_simd::default::F32x4;
 
+use rayon::ThreadPoolBuilder;
+
 use smallvec::SmallVec;
 
 use std::ffi::CString;
@@ -98,6 +100,10 @@ impl Window for MagicLeapWindow {
         self.framebuffer_id
     }
 
+    fn customize_rayon(&self, thread_pool_builder: ThreadPoolBuilder) -> ThreadPoolBuilder {
+        thread_pool_builder.start_handler(|id| unsafe { init_scene_thread(id) })
+    }
+
     fn mouse_position(&self) -> Point2DI32 {
         Point2DI32::new(0, 0)
     }
@@ -151,6 +157,10 @@ impl Window for MagicLeapWindow {
     }
 }
 
+extern "C" {
+    fn init_scene_thread(id: usize);
+}
+
 fn get_proc_address(s: &str) -> *const c_void {
     egl::get_proc_address(s) as *const c_void
 }

demo/magicleap/src/main.cpp

@@ -4,6 +4,9 @@
 #include <chrono>
 #include <cmath>
 
+#include <unistd.h>
+#include <sys/syscall.h>
+
 #ifndef EGL_EGLEXT_PROTOTYPES
 #define EGL_EGLEXT_PROTOTYPES
 #endif
@@ -28,6 +31,17 @@
 // Entry point to the Rust code
 extern "C" MLResult magicleap_pathfinder_demo(EGLDisplay egl_display, EGLContext egl_context);
 
+// Initialization of the scene thread
+extern "C" void init_scene_thread(uint64_t id) {
+  // https://forum.magicleap.com/hc/en-us/community/posts/360043120832-How-many-CPUs-does-an-immersive-app-have-access-to-?page=1#community_comment_360005035691
+  // We pin scene thread 0 to the Denver core.
+  if (id < 3) {
+    uint32_t DenverCoreAffinityMask = 1 << (2 + id); // Denver core is CPU2, A57s are CPU3 and 4.
+    pid_t ThreadId = gettid();
+    syscall(__NR_sched_setaffinity, ThreadId, sizeof(DenverCoreAffinityMask), &DenverCoreAffinityMask);
+  }
+}
+
 // Constants
 const char application_name[] = "com.mozilla.pathfinder.demo";