From 35b9f9f37b0142c4c41ec41571e06689587b0d6f Mon Sep 17 00:00:00 2001
From: Chris Kennelly <ckennelly@google.com>
Date: Wed, 19 Aug 2026 14:08:51 -0700
Subject: [PATCH] Place hot HintedTrackerList fields together.

lists_ will take up several cachelines, so we may end up accessing 3 distinct
cachelines, rather than putting bitmap_ and size_ together on just 1 (plus
potentially list_).

PiperOrigin-RevId: 967400706
---
 tcmalloc/hinted_tracker_lists.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tcmalloc/hinted_tracker_lists.h b/tcmalloc/hinted_tracker_lists.h
index 93afd68c8..ba9e33af7 100644
--- a/tcmalloc/hinted_tracker_lists.h
+++ b/tcmalloc/hinted_tracker_lists.h
@@ -145,9 +145,15 @@ class HintedTrackerLists {
   }
 
  private:
+#ifdef TCMALLOC_INTERNAL_LEGACY_LOCKING
   TrackerList lists_[N];
   size_t size_;
   Bitmap<N> nonempty_;
+#else
+  size_t size_;
+  Bitmap<N> nonempty_;
+  TrackerList lists_[N];
+#endif
 };
 
 }  // namespace tcmalloc_internal