Add elision and barrier metrics

softdevteam · Feb 10, 2025 · 0275994 · 0275994
1 parent dddcb72
commit 0275994
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Showing 3 changed files with 18 additions and 0 deletions.
diff --git a/library/alloc/src/alloc.rs b/library/alloc/src/alloc.rs
@@ -23,6 +23,8 @@ use core::sync::atomic::AtomicU64;
 /// Global counters for various GC stats.
 pub static GC_COUNTERS: GcCounters = GcCounters {
     finalizers_registered: AtomicU64::new(0),
+    finalizers_elidable: AtomicU64::new(0),
+    barriers_visited: AtomicU64::new(0),
     allocated_gc: AtomicU64::new(0),
     allocated_boxed: AtomicU64::new(0),
     allocated_rc: AtomicU64::new(0),
@@ -35,6 +37,8 @@ pub static GC_COUNTERS: GcCounters = GcCounters {
 #[derive(Debug, Default)]
 pub struct GcCounters {
     pub finalizers_registered: AtomicU64,
+    pub finalizers_elidable: AtomicU64,
+    pub barriers_visited: AtomicU64,
     pub allocated_gc: AtomicU64,
     pub allocated_boxed: AtomicU64,
     pub allocated_rc: AtomicU64,

diff --git a/library/std/src/gc.rs b/library/std/src/gc.rs
@@ -166,6 +166,8 @@ pub struct GcStats {
     pub premopt_enabled: u8,
     pub num_finalizers_registered: u64,
     pub num_finalizers_completed: u64,
+    pub num_finalizers_elidable: u64,
+    pub num_barriers_visited: u64,
     pub num_allocated_gc: u64,
     pub num_allocated_boxed: u64,
     pub num_allocated_arc: u64,
@@ -199,6 +201,8 @@ pub fn stats() -> GcStats {
             .finalizers_registered
             .load(atomic::Ordering::Relaxed),
         num_finalizers_completed: unsafe { bdwgc::GC_finalized_total() },
+        num_finalizers_elidable: GC_COUNTERS.finalizers_elidable.load(atomic::Ordering::Relaxed),
+        num_barriers_visited: GC_COUNTERS.barriers_visited.load(atomic::Ordering::Relaxed),
         num_allocated_gc: GC_COUNTERS.allocated_gc.load(atomic::Ordering::Relaxed),
         num_allocated_boxed: GC_COUNTERS.allocated_boxed.load(atomic::Ordering::Relaxed),
         num_allocated_rc: GC_COUNTERS.allocated_rc.load(atomic::Ordering::Relaxed),
@@ -288,6 +292,8 @@ impl<T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<Gc<U>> for Gc<T> {}
 #[cfg(all(not(bootstrap), not(test), feature = "premature-finalizer-prevention"))]
 impl<T: ?Sized> Drop for Gc<T> {
     fn drop(&mut self) {
+        #[cfg(feature = "log-stats")]
+        GC_COUNTERS.barriers_visited.fetch_add(1, atomic::Ordering::Relaxed);
         keep_alive(self);
     }
 }
@@ -524,6 +530,10 @@ impl<T> Gc<T> {
 
             #[cfg(feature = "log-stats")]
             {
+                GC_COUNTERS.finalizers_elidable.fetch_add(
+                    crate::mem::needs_finalizer::<T>() as u64,
+                    atomic::Ordering::Relaxed,
+                );
                 GC_COUNTERS.finalizers_registered.fetch_add(1, atomic::Ordering::Relaxed);
             }
         }

diff --git a/library/std/src/rt.rs b/library/std/src/rt.rs
@@ -126,6 +126,8 @@ pub(crate) fn log_stats() {
         premature finalizer prevention enabled,\
         premopt enabled,\
         finalizers registered,\
+        finalizers completed,\
+        barriers visited,\
         Gc allocated,\
         Box allocated,\
         Rc allocated,\
@@ -139,6 +141,8 @@ pub(crate) fn log_stats() {
         stats.premopt_enabled,
         stats.num_finalizers_registered,
         stats.num_finalizers_completed,
+        stats.num_finalizers_elidable,
+        stats.num_barriers_visited,
         stats.num_allocated_gc,
         stats.num_allocated_boxed,
         stats.num_allocated_rc,