From 0dbb0f1a5ce6a9ec5213c85e5d4244cf5b061417 Mon Sep 17 00:00:00 2001
From: Jian J Wang <jian.j.wang@intel.com>
Date: Thu, 18 Jan 2018 15:29:01 +0800
Subject: [PATCH] UefiCpuPkg/CpuDxe: fix bad boot performance

If features like memory profile, protection and heap guard are enabled,
a lot of more memory page attributes update actions will happen than
usual. An unnecessary sync of CR0.WP setting among APs will then cause
worse performance in memory allocation action. Removing the calling of
SyncMemoryPageAttributesAp() in function DisableReadOnlyPageWriteProtect
and EnableReadOnlyPageWriteProtect can fix this problem. In DEBUG build
case, the boot performance can be boosted from 11 minute to 6 minute.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
---
 UefiCpuPkg/CpuDxe/CpuPageTable.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/UefiCpuPkg/CpuDxe/CpuPageTable.c b/UefiCpuPkg/CpuDxe/CpuPageTable.c
index 90d9823838..a33ac5519e 100644
--- a/UefiCpuPkg/CpuDxe/CpuPageTable.c
+++ b/UefiCpuPkg/CpuDxe/CpuPageTable.c
@@ -597,7 +597,6 @@ DisableReadOnlyPageWriteProtect (
   )
 {
   AsmWriteCr0 (AsmReadCr0() & ~BIT16);
-  SyncMemoryPageAttributesAp (SyncCpuDisableWriteProtection);
 }
 
 /**
@@ -609,7 +608,6 @@ EnableReadOnlyPageWriteProtect (
   )
 {
   AsmWriteCr0 (AsmReadCr0() | BIT16);
-  SyncMemoryPageAttributesAp (SyncCpuEnableWriteProtection);
 }
 
 /**