[dpdk-dev] [PATCH v1 1/2] app/test: remove unnecessary barriers for ring stress test

[Feifei Wang]

The variable "wrk_cmd" is a signal to control threads from running and
stopping. When worker lcores load "wrk_cmd == WRK_CMD_RUN", they start
running and when worker lcores load "wrk_cmd == WRK_CMD_STOP", they
stop.

For the wmb in test_mt1, no storing operations must keep the order
after storing "wrk_cmd". Thus the wmb is unnecessary.

For the rmb in test_worker, the parameters have been prepared when
worker lcores call "test_worker". It is unnessary to wait wrk_cmd to be
loaded, then the parameters can be loaded, So the rmb can be removed.

In the meanwhile, fix a typo. The note above storing "stop" into
"wrk_cmd" should be "stop test" rather than "start test".

Signed-off-by: Feifei Wang <feifei.wa...@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.w...@arm.com>
---
 app/test/test_ring_stress_impl.h | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/app/test/test_ring_stress_impl.h b/app/test/test_ring_stress_impl.h
index f9ca63b90..384555ef9 100644
--- a/app/test/test_ring_stress_impl.h
+++ b/app/test/test_ring_stress_impl.h
@@ -198,7 +198,6 @@ test_worker(void *arg, const char *fname, int32_t prcs)
        fill_ring_elm(&loc_elm, lc);
 
        while (wrk_cmd != WRK_CMD_RUN) {
-               rte_smp_rmb();
                rte_pause();
        }
 
@@ -357,13 +356,11 @@ test_mt1(int (*test)(void *))
 
        /* signal worker to start test */
        wrk_cmd = WRK_CMD_RUN;
-       rte_smp_wmb();
 
        usleep(run_time * US_PER_S);
 
-       /* signal worker to start test */
+       /* signal worker to stop test */
        wrk_cmd = WRK_CMD_STOP;
-       rte_smp_wmb();
 
        /* wait for workers and collect stats. */
        mc = rte_lcore_id();
-- 
2.17.1