From e22300ab3db213a01da0f57128e50e4519cd45f3 Mon Sep 17 00:00:00 2001
From: esigo <ehsan.sadroid@gmail.com>
Date: Thu, 25 Nov 2021 19:05:13 +0100
Subject: [PATCH 1/2] fix lock

---
 api/test/common/spinlock_benchmark.cc | 24 ++++++------------------
 1 file changed, 6 insertions(+), 18 deletions(-)

diff --git a/api/test/common/spinlock_benchmark.cc b/api/test/common/spinlock_benchmark.cc
index 95c3f7c7af..2b4e2d52de 100644
--- a/api/test/common/spinlock_benchmark.cc
+++ b/api/test/common/spinlock_benchmark.cc
@@ -103,29 +103,17 @@ static void BM_ProcYieldSpinLockThrashing(benchmark::State &s)
 // SpinLock thrashing with thread::yield() after N spins.
 static void BM_ThreadYieldSpinLockThrashing(benchmark::State &s)
 {
-  std::atomic<bool> mutex(false);
-  SpinThrash<std::atomic<bool>>(
+  std::atomic_flag mutex = ATOMIC_FLAG_INIT;
+  SpinThrash<std::atomic_flag>(
       s, mutex,
-      [](std::atomic<bool> &l) {
-        if (!l.exchange(true, std::memory_order_acq_rel))
+      [](std::atomic_flag &l) {
+        while (l.test_and_set(std::memory_order_acq_rel))
         {
-          return;
-        }
-        for (std::size_t i = 0; i < 128; ++i)
-        {
-          if (!l.load(std::memory_order_acquire) && !l.exchange(true, std::memory_order_acq_rel))
-          {
-            return;
-          }
-
-          if (i % 32 == 0)
-          {
-            std::this_thread::yield();
-          }
+          ;
         }
         std::this_thread::yield();
       },
-      [](std::atomic<bool> &l) { l.store(false, std::memory_order_release); });
+      [](std::atomic_flag &l) { l.clear(std::memory_order_release); });
 }
 
 // Run the benchmarks at 2x thread/core and measure the amount of time to thrash around.

From 1b8b635fd3fb980423a14a66036a82ce55a7a27c Mon Sep 17 00:00:00 2001
From: Oblivion <ehsan.sadroid@gmail.com>
Date: Wed, 1 Dec 2021 20:04:14 +0000
Subject: [PATCH 2/2] add yield

---
 api/test/common/spinlock_benchmark.cc | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/api/test/common/spinlock_benchmark.cc b/api/test/common/spinlock_benchmark.cc
index 2b4e2d52de..28692bee56 100644
--- a/api/test/common/spinlock_benchmark.cc
+++ b/api/test/common/spinlock_benchmark.cc
@@ -100,16 +100,21 @@ static void BM_ProcYieldSpinLockThrashing(benchmark::State &s)
       [](SpinLockMutex &m) { m.unlock(); });
 }
 
-// SpinLock thrashing with thread::yield() after N spins.
+// SpinLock thrashing with thread::yield().
 static void BM_ThreadYieldSpinLockThrashing(benchmark::State &s)
 {
   std::atomic_flag mutex = ATOMIC_FLAG_INIT;
   SpinThrash<std::atomic_flag>(
       s, mutex,
       [](std::atomic_flag &l) {
+        uint32_t try_count = 0;
         while (l.test_and_set(std::memory_order_acq_rel))
         {
-          ;
+          ++try_count;
+          if (try_count % 32)
+          {
+            std::this_thread::yield();
+          }
         }
         std::this_thread::yield();
       },