From c1ebf893e32a0a77e820484d48a903523fef7c1b Mon Sep 17 00:00:00 2001
From: Vasily Tarasov <tarasov@vasily.name>
Date: Fri, 10 Jun 2016 14:33:48 -0400
Subject: [PATCH] Adding volatile modifier to tmp variable in memory test

Issue explanation:

./sysbench/sysbench --test=memory --num-threads=16 \
		    --memory-block-size=268435456 \
		    --memory-total-size=137438953472 \
		    --memory-oper=read \
		    --memory-access-mode=seq \
		    --memory-scope=local run

Without this commit the time to run the above command is 0.0004 seconds.
With this commit the time is greater than 3 seconds.  Essentially,
without the volatile modifier, the compiler optimizes read access so
that no real access happens.

Upstream-Status: Backport [part of v1.0.0 https://github.com/akopytov/sysbench/commit/8753cb93be4c0b81a20b704ced91e7a422da52b1]

(cherry picked from commit 8753cb93be4c0b81a20b704ced91e7a422da52b1)
Signed-off-by: massimo toscanelli <massimo.toscanelli@leica-geosystems.com>
---
 sysbench/tests/memory/sb_memory.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sysbench/tests/memory/sb_memory.c b/sysbench/tests/memory/sb_memory.c
index 2e8998f..7d22bb9 100644
--- a/sysbench/tests/memory/sb_memory.c
+++ b/sysbench/tests/memory/sb_memory.c
@@ -244,7 +244,7 @@ sb_request_t memory_get_request(int tid)
 int memory_execute_request(sb_request_t *sb_req, int thread_id)
 {
   sb_mem_request_t    *mem_req = &sb_req->u.mem_request;
-  int                 tmp = 0;
+  volatile int        tmp = 0;
   int                 idx; 
   int                 *buf, *end;
   log_msg_t           msg;