Re: [Qemu-devel] [PATCH v6 26/35] tests: add atomic_add-bench

[Emilio G. Cota]

On Tue, Oct 11, 2016 at 14:40:52 -0500, Richard Henderson wrote:
> From: "Emilio G. Cota" <address@hidden>
> 
> With this microbenchmark we can measure the overhead of emulating atomic
> instructions with a configurable degree of contention.
> 
> The benchmark spawns $n threads, each performing $o atomic ops (additions)
> in a loop. Each atomic operation is performed on a different cache line
> (assuming lines are 64b long) that is randomly selected from a range [0, $r).
> 
> [ Note: each $foo corresponds to a -foo flag ]
> 
> Signed-off-by: Emilio G. Cota <address@hidden>
> Signed-off-by: Richard Henderson <address@hidden>
> Message-Id: <address@hidden>

Can you please fix up this patch with the below? It does the
same as we're doing in qht-bench:
  http://lists.nongnu.org/archive/html/qemu-devel/2016-10/msg03034.html

Thanks,

                Emilio

commit e3f226e427358778c57a102a3c5e35373f1f98cf
Author: Emilio G. Cota <address@hidden>
Date:   Fri Oct 14 17:15:25 2016 -0400

    atomic_add-bench: relax test_start/stop atomic accesses
    
    Signed-off-by: Emilio G. Cota <address@hidden>

diff --git a/tests/atomic_add-bench.c b/tests/atomic_add-bench.c
index 69c59ad..caa1e8e 100644
--- a/tests/atomic_add-bench.c
+++ b/tests/atomic_add-bench.c
@@ -50,7 +50,7 @@ static void *thread_func(void *arg)
     struct thread_info *info = arg;
 
     atomic_inc(&n_ready_threads);
-    while (!atomic_mb_read(&test_start)) {
+    while (!atomic_read(&test_start)) {
         cpu_relax();
     }
 
@@ -72,11 +72,11 @@ static void run_test(void)
     while (atomic_read(&n_ready_threads) != n_threads) {
         cpu_relax();
     }
-    atomic_mb_set(&test_start, true);
+    atomic_set(&test_start, true);
     do {
         remaining = sleep(duration);
     } while (remaining);
-    atomic_mb_set(&test_stop, true);
+    atomic_set(&test_stop, true);
 
     for (i = 0; i < n_threads; i++) {
         qemu_thread_join(&threads[i]);