From 141162907f14f4bd68a239f9e692b8583488f65d Mon Sep 17 00:00:00 2001
From: Yibo Cai <yibo.cai@arm.com>
Date: Fri, 15 Nov 2019 01:51:28 +0000
Subject: [PATCH] innobase/os: refine os_total_large_mem_allocated with c++11
 atomics

Though only atomicity is required, current code uses gcc __sync_xxx
builtins which introduces unnecessary memory barriers. Refine with
C++11 relaxed memory order.
---
 storage/innobase/include/os0proc.h |  3 ++-
 storage/innobase/os/os0proc.cc     | 16 ++++++++--------
 storage/innobase/srv/srv0srv.cc    |  2 +-
 3 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/storage/innobase/include/os0proc.h b/storage/innobase/include/os0proc.h
index 13633bb..66356fa 100644
--- a/storage/innobase/include/os0proc.h
+++ b/storage/innobase/include/os0proc.h
@@ -35,6 +35,7 @@ this program; if not, write to the Free Software Foundation, Inc.,
 #define os0proc_h
 
 #include "univ.i"
+#include "os0atomic.h"
 
 #ifdef UNIV_LINUX
 #include <sys/ipc.h>
@@ -46,7 +47,7 @@ typedef unsigned long int os_process_id_t;
 
 /** The total amount of memory currently allocated from the operating
 system with os_mem_alloc_large(). */
-extern ulint os_total_large_mem_allocated;
+extern os_atomic_t<ulint> os_total_large_mem_allocated;
 
 /** Whether to use large pages in the buffer pool */
 extern bool os_use_large_pages;
diff --git a/storage/innobase/os/os0proc.cc b/storage/innobase/os/os0proc.cc
index ed46602..3aa1a7f 100644
--- a/storage/innobase/os/os0proc.cc
+++ b/storage/innobase/os/os0proc.cc
@@ -52,7 +52,7 @@ MAP_ANON but MAP_ANON is marked as deprecated */
 
 /** The total amount of memory currently allocated from the operating
 system with os_mem_alloc_large(). */
-ulint os_total_large_mem_allocated = 0;
+os_atomic_t<ulint> os_total_large_mem_allocated;
 
 /** Whether to use large pages in the buffer pool */
 bool os_use_large_pages;
@@ -110,7 +110,7 @@ void *os_mem_alloc_large(ulint *n) {
 
   if (ptr) {
     *n = size;
-    os_atomic_increment_ulint(&os_total_large_mem_allocated, size);
+    os_total_large_mem_allocated.fetch_add(size, order_relaxed);
 
     UNIV_MEM_ALLOC(ptr, size);
     return (ptr);
@@ -137,7 +137,7 @@ skip:
                                " Windows error "
                             << GetLastError();
   } else {
-    os_atomic_increment_ulint(&os_total_large_mem_allocated, size);
+    os_total_large_mem_allocated.fetch_add(size, order_relaxed);
     UNIV_MEM_ALLOC(ptr, size);
   }
 #else
@@ -154,7 +154,7 @@ skip:
                              << errno;
     ptr = NULL;
   } else {
-    os_atomic_increment_ulint(&os_total_large_mem_allocated, size);
+    os_total_large_mem_allocated.fetch_add(size, order_relaxed);
     UNIV_MEM_ALLOC(ptr, size);
   }
 #endif
@@ -165,11 +165,11 @@ skip:
 @param[in]	ptr	pointer returned by os_mem_alloc_large()
 @param[in]	size	size returned by os_mem_alloc_large() */
 void os_mem_free_large(void *ptr, ulint size) {
-  ut_a(os_total_large_mem_allocated >= size);
+  ut_a(os_total_large_mem_allocated.load(order_relaxed) >= size);
 
 #if defined HAVE_LINUX_LARGE_PAGES && defined UNIV_LINUX
   if (os_use_large_pages && os_large_page_size && !shmdt(ptr)) {
-    os_atomic_decrement_ulint(&os_total_large_mem_allocated, size);
+    os_total_large_mem_allocated.fetch_sub(size, order_relaxed);
     UNIV_MEM_FREE(ptr, size);
     return;
   }
@@ -181,7 +181,7 @@ void os_mem_free_large(void *ptr, ulint size) {
     ib::error(ER_IB_MSG_857) << "VirtualFree(" << ptr << ", " << size
                              << ") failed; Windows error " << GetLastError();
   } else {
-    os_atomic_decrement_ulint(&os_total_large_mem_allocated, size);
+    os_total_large_mem_allocated.fetch_sub(size, order_relaxed);
     UNIV_MEM_FREE(ptr, size);
   }
 #elif !defined OS_MAP_ANON
@@ -197,7 +197,7 @@ void os_mem_free_large(void *ptr, ulint size) {
                                 " errno "
                              << errno;
   } else {
-    os_atomic_decrement_ulint(&os_total_large_mem_allocated, size);
+    os_total_large_mem_allocated.fetch_sub(size, order_relaxed);
     UNIV_MEM_FREE(ptr, size);
   }
 #endif
diff --git a/storage/innobase/srv/srv0srv.cc b/storage/innobase/srv/srv0srv.cc
index 9e885bd..27ba3b1 100644
--- a/storage/innobase/srv/srv0srv.cc
+++ b/storage/innobase/srv/srv0srv.cc
@@ -1397,7 +1397,7 @@ ibool srv_printf_innodb_monitor(
           "Total large memory allocated " ULINTPF
           "\n"
           "Dictionary memory allocated " ULINTPF "\n",
-          os_total_large_mem_allocated, dict_sys->size);
+          os_total_large_mem_allocated.load(order_relaxed), dict_sys->size);
 
   buf_print_io(file);
 
-- 
2.7.4