[RFC,v1,1/6] app/eventdev: fix SMP barrier bugs for perf test
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Commit Message
This patch fixes RTE SMP barrier bugs for the perf test of eventdev.
For the "perf_process_last_stage" function, wmb after storing
processed_pkts should be moved before it. This is because the worker
lcore should ensure it has really finished data processing, e.g. event
stored into buffers, before the shared variables "w->processed_pkts"are
stored.
For the "perf_process_last_stage_latency", on the one hand, the wmb
should be moved before storing into "w->processed_pkts". The reason is
the same as above. But on the other hand, for "w->latency", wmb is
unnecessary due to data dependency.
Fixes: 2369f73329f8 ("app/testeventdev: add perf queue worker functions")
Cc: jerinj@marvell.com
Cc: stable@dpdk.org
Signed-off-by: Feifei Wang <feifei.wang2@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
---
app/test-eventdev/test_perf_common.h | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
@@ -97,8 +97,13 @@ perf_process_last_stage(struct rte_mempool *const pool,
void *bufs[], int const buf_sz, uint8_t count)
{
bufs[count++] = ev->event_ptr;
- w->processed_pkts++;
+
+ /* wmb here ensures event_prt is stored before
+ * updating the number of processed packets
+ * for worker lcores
+ */
rte_smp_wmb();
+ w->processed_pkts++;
if (unlikely(count == buf_sz)) {
count = 0;
@@ -116,6 +121,12 @@ perf_process_last_stage_latency(struct rte_mempool *const pool,
struct perf_elt *const m = ev->event_ptr;
bufs[count++] = ev->event_ptr;
+
+ /* wmb here ensures event_prt is stored before
+ * updating the number of processed packets
+ * for worker lcores
+ */
+ rte_smp_wmb();
w->processed_pkts++;
if (unlikely(count == buf_sz)) {
@@ -127,7 +138,6 @@ perf_process_last_stage_latency(struct rte_mempool *const pool,
}
w->latency += latency;
- rte_smp_wmb();
return count;
}