From 981d4c77040d2648d69f7ee862737183386c4b88 Mon Sep 17 00:00:00 2001
From: Jianpeng Ma <jianpeng.ma@intel.com>
Date: Fri, 19 Jul 2019 21:20:19 +0800
Subject: [PATCH] os/bluestore: Reduce unnecessary wakeups.

Add bool kv_sync_in_progress to indicate thread kv_sync_thread
is running or waiting. Only wake up if thread waiting.

Signed-off-by: Jianpeng Ma <jianpeng.ma@intel.com>
---
 src/os/bluestore/BlueStore.cc | 26 +++++++++++++++++++++-----
 src/os/bluestore/BlueStore.h  |  1 +
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/src/os/bluestore/BlueStore.cc b/src/os/bluestore/BlueStore.cc
index 10742c7dd60a4..4dac4bff8c4f3 100644
--- a/src/os/bluestore/BlueStore.cc
+++ b/src/os/bluestore/BlueStore.cc
@@ -9912,7 +9912,10 @@ void BlueStore::_txc_state_proc(TransContext *txc)
       {
 	std::lock_guard l(kv_lock);
 	kv_queue.push_back(txc);
-	kv_cond.notify_one();
+	if (!kv_sync_in_progress) {
+	  kv_sync_in_progress = true;
+	  kv_cond.notify_one();
+	}
 	if (txc->state != TransContext::STATE_KV_SUBMITTED) {
 	  kv_queue_unsubmitted.push_back(txc);
 	  ++txc->osr->kv_committing_serially;
@@ -10294,7 +10297,10 @@ void BlueStore::_osr_drain_preceding(TransContext *txc)
   {
     // wake up any previously finished deferred events
     std::lock_guard l(kv_lock);
-    kv_cond.notify_one();
+    if (!kv_sync_in_progress) {
+      kv_sync_in_progress = true;
+      kv_cond.notify_one();
+    }
   }
   osr->drain_preceding(txc);
   --deferred_aggressive;
@@ -10317,7 +10323,10 @@ void BlueStore::_osr_drain(OpSequencer *osr)
   {
     // wake up any previously finished deferred events
     std::lock_guard l(kv_lock);
-    kv_cond.notify_one();
+    if (!kv_sync_in_progress) {
+      kv_sync_in_progress = true;
+      kv_cond.notify_one();
+    }
   }
   osr->drain();
   --deferred_aggressive;
@@ -10450,6 +10459,7 @@ void BlueStore::_kv_sync_thread()
       if (kv_stop)
 	break;
       dout(20) << __func__ << " sleep" << dendl;
+      kv_sync_in_progress = false;
       kv_cond.wait(l);
       dout(20) << __func__ << " wake" << dendl;
     } else {
@@ -10930,7 +10940,10 @@ void BlueStore::_deferred_aio_finish(OpSequencer *osr)
   // catch us on the next commit anyway.
   if (deferred_aggressive) {
     std::lock_guard l(kv_lock);
-    kv_cond.notify_one();
+    if (!kv_sync_in_progress) {
+      kv_sync_in_progress = true;
+      kv_cond.notify_one();
+    }
   }
 }
 
@@ -11048,7 +11061,10 @@ int BlueStore::queue_transactions(
       {
 	// wake up any previously finished deferred events
 	std::lock_guard l(kv_lock);
-	kv_cond.notify_one();
+	if (!kv_sync_in_progress) {
+	  kv_sync_in_progress = true;
+	  kv_cond.notify_one();
+	}
       }
       throttle_deferred_bytes.get(txc->cost);
       --deferred_aggressive;
diff --git a/src/os/bluestore/BlueStore.h b/src/os/bluestore/BlueStore.h
index 52b2d701b14f0..d3ed51e860181 100644
--- a/src/os/bluestore/BlueStore.h
+++ b/src/os/bluestore/BlueStore.h
@@ -1951,6 +1951,7 @@ private:
   deque<TransContext*> kv_queue_unsubmitted; ///< ready, need submit by kv thread
   deque<TransContext*> kv_committing;        ///< currently syncing
   deque<DeferredBatch*> deferred_done_queue;   ///< deferred ios done
+  bool kv_sync_in_progress = false;
 
   KVFinalizeThread kv_finalize_thread;
   ceph::mutex kv_finalize_lock = ceph::make_mutex("BlueStore::kv_finalize_lock");
-- 
2.39.5