From c1ebf893e32a0a77e820484d48a903523fef7c1b Mon Sep 17 00:00:00 2001
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From: Vasily Tarasov <tarasov@vasily.name>
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Date: Fri, 10 Jun 2016 14:33:48 -0400
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Subject: [PATCH] Adding volatile modifier to tmp variable in memory test
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Issue explanation:
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./sysbench/sysbench --test=memory --num-threads=16 \
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--memory-block-size=268435456 \
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--memory-total-size=137438953472 \
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--memory-oper=read \
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--memory-access-mode=seq \
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--memory-scope=local run
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Without this commit the time to run the above command is 0.0004 seconds.
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With this commit the time is greater than 3 seconds. Essentially,
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without the volatile modifier, the compiler optimizes read access so
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that no real access happens.
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Upstream-Status: Backport [part of v1.0.0 https://github.com/akopytov/sysbench/commit/8753cb93be4c0b81a20b704ced91e7a422da52b1]
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(cherry picked from commit 8753cb93be4c0b81a20b704ced91e7a422da52b1)
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Signed-off-by: massimo toscanelli <massimo.toscanelli@leica-geosystems.com>
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---
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sysbench/tests/memory/sb_memory.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/sysbench/tests/memory/sb_memory.c b/sysbench/tests/memory/sb_memory.c
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index 2e8998f..7d22bb9 100644
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--- a/sysbench/tests/memory/sb_memory.c
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+++ b/sysbench/tests/memory/sb_memory.c
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@@ -244,7 +244,7 @@ sb_request_t memory_get_request(int tid)
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int memory_execute_request(sb_request_t *sb_req, int thread_id)
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{
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sb_mem_request_t *mem_req = &sb_req->u.mem_request;
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- int tmp = 0;
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+ volatile int tmp = 0;
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int idx;
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int *buf, *end;
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log_msg_t msg;
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