From: Wei Jin <wjin.cn@gmail.com>
Date: Fri, 6 Jan 2017 09:35:08 +0000 (+0800)
Subject: msg/async: avoid atomic variable overhead
X-Git-Tag: v12.0.0~228^2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=2421010a47b8121d53132f5608afb42401e9a17c;p=ceph.git

msg/async: avoid atomic variable overhead

1) there is already a lock to protect the count
2) no need to send signal during each callback

Signed-off-by: Wei Jin <wjin.cn@gmail.com>
---

diff --git a/src/msg/async/Stack.cc b/src/msg/async/Stack.cc
index d81241eb8aaf..26d119b999cd 100644
--- a/src/msg/async/Stack.cc
+++ b/src/msg/async/Stack.cc
@@ -174,7 +174,7 @@ void NetworkStack::stop()
 class C_drain : public EventCallback {
   Mutex drain_lock;
   Cond drain_cond;
-  std::atomic<unsigned> drain_count;
+  unsigned drain_count;
 
  public:
   explicit C_drain(size_t c)
@@ -183,11 +183,11 @@ class C_drain : public EventCallback {
   void do_request(int id) {
     Mutex::Locker l(drain_lock);
     drain_count--;
-    drain_cond.Signal();
+    if (drain_count == 0) drain_cond.Signal();
   }
   void wait() {
     Mutex::Locker l(drain_lock);
-    while (drain_count.load())
+    while (drain_count)
       drain_cond.Wait(drain_lock);
   }
 };