[dpdk-dev] [RFC PATCH v1 2/6] app/eventdev: remove unnecessary barriers for perf test

[Feifei Wang]

For "processed_pkts" and "total_latency" functions, no operations should
keep the order that being executed before loading
"worker[i].processed_pkts". Thus rmb is unnecessary before loading.

For "perf_launch_lcores" function, wmb after that the main lcore
updates the variable "t->done", which represents the end of the test
signal, is unnecessary. Because after the main lcore updates this
siginal variable, it will jump out of the launch function loop, and wait
other lcores stop or return error in the main function(evt_main.c).
During this time, there is no important storing operation and thus no
need for wmb.

Signed-off-by: Feifei Wang <feifei.wa...@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.w...@arm.com>
---
 app/test-eventdev/test_perf_common.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/app/test-eventdev/test_perf_common.c 
b/app/test-eventdev/test_perf_common.c
index 955edb752..34cded373 100644
--- a/app/test-eventdev/test_perf_common.c
+++ b/app/test-eventdev/test_perf_common.c
@@ -224,7 +224,6 @@ processed_pkts(struct test_perf *t)
        uint8_t i;
        uint64_t total = 0;
 
-       rte_smp_rmb();
        for (i = 0; i < t->nb_workers; i++)
                total += t->worker[i].processed_pkts;
 
@@ -237,7 +236,6 @@ total_latency(struct test_perf *t)
        uint8_t i;
        uint64_t total = 0;
 
-       rte_smp_rmb();
        for (i = 0; i < t->nb_workers; i++)
                total += t->worker[i].latency;
 
@@ -327,7 +325,6 @@ perf_launch_lcores(struct evt_test *test, struct 
evt_options *opt,
                                        opt->prod_type ==
                                        EVT_PROD_TYPE_EVENT_TIMER_ADPTR) {
                                        t->done = true;
-                                       rte_smp_wmb();
                                        break;
                                }
                        }
@@ -341,7 +338,6 @@ perf_launch_lcores(struct evt_test *test, struct 
evt_options *opt,
                                rte_event_dev_dump(opt->dev_id, stdout);
                                evt_err("No schedules for seconds, deadlock");
                                t->done = true;
-                               rte_smp_wmb();
                                break;
                        }
                        dead_lock_remaining = remaining;
-- 
2.17.1