Hi, Sriram

Do you have any performance data about this change for Network IO case?

Thanks
Feng

-----Original Message-----
From: Subramanian, Sriram (System FW, HP Servers) [mailto:srira...@hpe.com] 
Sent: Thursday, September 17, 2015 14:07
To: edk2-devel@lists.01.org
Cc: El-Haj-Mahmoud, Samer; Tian, Feng
Subject: [edk2] [PATCH v1] MdeModulePkg: Remove event from protocol database 
only if registered

In a CloseEvent, an UnregisterProtocolNotify is done unconditionally.
There is a penalty associated with searching the protocol database on every 
CloseEvent and impacts performance, especially during Network IO. Unregister 
needs to be done only if the Event is for a RegisterProtocolNotify.

So extend the ExFlag in IEVENT to a UINT8 and define new flags that can be set 
to indicate if the Event is part of a group, or registered on a protocol 
notify. Then in CloseEvent, call UnregisterProtocolNotify only if the register 
protocol notify flag is set.

Contributed-under: TianoCore Contribution Agreement 1.0

Signed-off-by: Samer El-Haj-Mahmoud <samer.el-haj-mahm...@hpe.com>
---
Index: MdeModulePkg/Core/Dxe/Event/Event.c
===================================================================
--- MdeModulePkg/Core/Dxe/Event/Event.c (revision 18494)
+++ MdeModulePkg/Core/Dxe/Event/Event.c (working copy)
@@ -2,6 +2,7 @@
   UEFI Event support functions implemented in this file.
 
 Copyright (c) 2006 - 2014, Intel Corporation. All rights reserved.<BR>
+(C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
 This program and the accompanying materials  are licensed and made available 
under the terms and conditions of the BSD License  which accompanies this 
distribution.  The full text of the license may be found at @@ -477,7 +478,7 @@
   IEvent->NotifyContext  = (VOID *)NotifyContext;
   if (EventGroup != NULL) {
     CopyGuid (&IEvent->EventGroup, EventGroup);
-    IEvent->ExFlag = TRUE;
+    IEvent->ExFlag |= EVT_EXFLAG_EVENT_GROUP;
   }
 
   *Event = IEvent;
@@ -554,7 +555,7 @@
     // If signalling type is a notify function, queue it
     //
     if ((Event->Type & EVT_NOTIFY_SIGNAL) != 0) {
-      if (Event->ExFlag) {
+      if ((Event->ExFlag & EVT_EXFLAG_EVENT_GROUP) != 0) {
         //
         // The CreateEventEx() style requires all members of the Event Group
         //  to be signaled.
@@ -764,7 +765,9 @@
   //
   // If the event is registered on a protocol notify, then remove it from the 
protocol database
   //
-  CoreUnregisterProtocolNotify (Event);
+  if ((Event->ExFlag & EVT_EXFLAG_EVENT_PROTOCOL_NOTIFICATION) != 0) {
+    CoreUnregisterProtocolNotify (Event);  }
 
   Status = CoreFreePool (Event);
   ASSERT_EFI_ERROR (Status);
Index: MdeModulePkg/Core/Dxe/Event/Event.h
===================================================================
--- MdeModulePkg/Core/Dxe/Event/Event.h (revision 18494)
+++ MdeModulePkg/Core/Dxe/Event/Event.h (working copy)
@@ -2,6 +2,7 @@
   UEFI Event support functions and structure.
 
 Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
+(C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
 This program and the accompanying materials  are licensed and made available 
under the terms and conditions of the BSD License  which accompanies this 
distribution.  The full text of the license may be found at @@ -19,6 +20,14 @@
 #define VALID_TPL(a)            ((a) <= TPL_HIGH_LEVEL)
 extern  UINTN                   gEventPending;
 
+///
+/// Set if Event is part of an event group ///
+#define EVT_EXFLAG_EVENT_GROUP                    0x01
+///
+/// Set if Event is registered on a protocol notify ///
+#define EVT_EXFLAG_EVENT_PROTOCOL_NOTIFICATION    0x02
 
 //
 // EFI_EVENT
@@ -50,7 +59,7 @@
   VOID                    *NotifyContext;
   EFI_GUID                EventGroup;
   LIST_ENTRY              NotifyLink;
-  BOOLEAN                 ExFlag;
+  UINT8                   ExFlag;
   ///
   /// A list of all runtime events
   ///
Index: MdeModulePkg/Core/Dxe/Hand/Notify.c
===================================================================
--- MdeModulePkg/Core/Dxe/Hand/Notify.c (revision 18494)
+++ MdeModulePkg/Core/Dxe/Hand/Notify.c (working copy)
@@ -2,6 +2,7 @@
   Support functions for UEFI protocol notification infrastructure.
 
 Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
+(C) Copyright 2015 Hewlett Packard Enterprise Development LP<BR>
 This program and the accompanying materials  are licensed and made available 
under the terms and conditions of the BSD License  which accompanies this 
distribution.  The full text of the license may be found at @@ -14,6 +15,7 @@
 
 #include "DxeMain.h"
 #include "Handle.h"
+#include "Event.h"
 
 
 /**
@@ -136,6 +138,7 @@
     ProtNotify = AllocatePool (sizeof(PROTOCOL_NOTIFY));
     if (ProtNotify != NULL) {
 
+      ((IEVENT *)Event)->ExFlag |=
+ EVT_EXFLAG_EVENT_PROTOCOL_NOTIFICATION;
       ProtNotify->Signature = PROTOCOL_NOTIFY_SIGNATURE;
       ProtNotify->Protocol = ProtEntry;
       ProtNotify->Event = Event;


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