[libcxx-commits] [libcxx] [libc++] Disable atomic_wait benchmarks outside of dry-run mode (PR #158631)

[Louis Dionne via libcxx-commits]

https://github.com/ldionne created https://github.com/llvm/llvm-project/pull/158631

The atomic_wait benchmarks are great, but they tend to overload the system they're running on. For that reason, we can't run them on our CI infrastructure on a regular basis.

Instead of removing them, make them unsupported outside of dry-running, which allows keeping the benchmarks around and ensuring they don't rot, but doesn't run them along with the other benchmarks. If we need to investigate atomic_wait performance, it's trivial to mark the benchmark as supported and run it for local investigations.

This is an alternative to https://github.com/llvm/llvm-project/pull/158289.

>From f617bc0efe0d52436828ba10e7b2cfa73b5c10eb Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Mon, 15 Sep 2025 08:53:21 -0400
Subject: [PATCH] [libc++] Disable atomic_wait benchmarks outside of dry-run
 mode

The atomic_wait benchmarks are great, but they tend to overload the
system they're running on. For that reason, we can't run them on our
CI infrastructure on a regular basis.

Instead of removing them, make them unsupported outside of dry-running,
which allows keeping the benchmarks around and ensuring they don't rot,
but doesn't run them along with the other benchmarks. If we need to
investigate atomic_wait performance, it's trivial to mark the benchmark
as supported and run it for local investigations.

This is an alternative to https://github.com/llvm/llvm-project/pull/158289.
---
 .../test/benchmarks/atomic_wait_1_waiter_1_notifier.bench.cpp | 4 ++++
 .../test/benchmarks/atomic_wait_N_waiter_N_notifier.bench.cpp | 4 ++++
 .../benchmarks/atomic_wait_multi_waiter_1_notifier.bench.cpp  | 4 ++++
 libcxx/test/benchmarks/atomic_wait_vs_mutex_lock.bench.cpp    | 4 ++++
 4 files changed, 16 insertions(+)

diff --git a/libcxx/test/benchmarks/atomic_wait_1_waiter_1_notifier.bench.cpp b/libcxx/test/benchmarks/atomic_wait_1_waiter_1_notifier.bench.cpp
index c3d7e6511925d..5c82b8e8e9af6 100644
--- a/libcxx/test/benchmarks/atomic_wait_1_waiter_1_notifier.bench.cpp
+++ b/libcxx/test/benchmarks/atomic_wait_1_waiter_1_notifier.bench.cpp
@@ -8,6 +8,10 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 
+// This benchmark is very expensive and we don't want to run it on a regular basis,
+// only to ensure the code doesn't rot.
+// REQUIRES: enable-benchmarks=dry-run
+
 #include "atomic_wait_helper.h"
 
 #include <atomic>
diff --git a/libcxx/test/benchmarks/atomic_wait_N_waiter_N_notifier.bench.cpp b/libcxx/test/benchmarks/atomic_wait_N_waiter_N_notifier.bench.cpp
index d9b9aa212f602..4d6547418e767 100644
--- a/libcxx/test/benchmarks/atomic_wait_N_waiter_N_notifier.bench.cpp
+++ b/libcxx/test/benchmarks/atomic_wait_N_waiter_N_notifier.bench.cpp
@@ -8,6 +8,10 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 
+// This benchmark is very expensive and we don't want to run it on a regular basis,
+// only to ensure the code doesn't rot.
+// REQUIRES: enable-benchmarks=dry-run
+
 #include "atomic_wait_helper.h"
 
 #include <atomic>
diff --git a/libcxx/test/benchmarks/atomic_wait_multi_waiter_1_notifier.bench.cpp b/libcxx/test/benchmarks/atomic_wait_multi_waiter_1_notifier.bench.cpp
index a14a6a2ad9c98..f8288cb4c8020 100644
--- a/libcxx/test/benchmarks/atomic_wait_multi_waiter_1_notifier.bench.cpp
+++ b/libcxx/test/benchmarks/atomic_wait_multi_waiter_1_notifier.bench.cpp
@@ -8,6 +8,10 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 
+// This benchmark is very expensive and we don't want to run it on a regular basis,
+// only to ensure the code doesn't rot.
+// REQUIRES: enable-benchmarks=dry-run
+
 #include "atomic_wait_helper.h"
 
 #include <atomic>
diff --git a/libcxx/test/benchmarks/atomic_wait_vs_mutex_lock.bench.cpp b/libcxx/test/benchmarks/atomic_wait_vs_mutex_lock.bench.cpp
index a554c721df017..9849ffa7e038d 100644
--- a/libcxx/test/benchmarks/atomic_wait_vs_mutex_lock.bench.cpp
+++ b/libcxx/test/benchmarks/atomic_wait_vs_mutex_lock.bench.cpp
@@ -8,6 +8,10 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 
+// This benchmark is very expensive and we don't want to run it on a regular basis,
+// only to ensure the code doesn't rot.
+// REQUIRES: enable-benchmarks=dry-run
+
 #include <atomic>
 #include <cstdint>
 #include <mutex>