From 5044b4419c4b7001638ee8d6f14c44b2d36482f6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Constantin=20F=C3=BCrst?= <c@fuersten.info>
Date: Wed, 7 Feb 2024 18:19:30 +0100
Subject: [PATCH] make load balancing thread-local to reduce atomic cost

---
 qdp_project/src/utils/BenchmarkHelpers.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/qdp_project/src/utils/BenchmarkHelpers.cpp b/qdp_project/src/utils/BenchmarkHelpers.cpp
index 676f68c..903eba5 100644
--- a/qdp_project/src/utils/BenchmarkHelpers.cpp
+++ b/qdp_project/src/utils/BenchmarkHelpers.cpp
@@ -38,13 +38,13 @@ std::vector<int> CopyMethodPolicy(const int numa_dst_node, const int numa_src_no
     // as submission cost matters for low transfer size
 
     if (data_size < 16_MiB) {
-        static std::atomic<int> last_node = 0;
-        const int node = last_node.fetch_add(1) % 4;
+        static thread_local int last_node = 0;
+        const int node = last_node++ % 4;
         return std::vector<int>{ node };
     }
     else {
-        static std::atomic<int> last_group = 0;
-        const int group = last_group.fetch_add(1) % 2;
+        static thread_local int last_group = 0;
+        const int group = last_group++ % 2;
         return group == 0 ? std::vector<int>{ 0, 1 } : std::vector<int>{ 2, 3 };
     }
 }