[dpdk-dev] [PATCH v2] examples/l3fwd: skip TX queue drain on first iteration

[Kathleen Capella <kathleen.capella@arm.com>]

Initialize prev_tsc to cur_tsc. This avoids running the TX queue drain
in the first iteration of the packet processing loop.

Signed-off-by: Kathleen Capella <kathleen.capella@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
---
 examples/l3fwd/l3fwd_em.c  | 9 +++++----
 examples/l3fwd/l3fwd_lpm.c | 9 +++++----
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/examples/l3fwd/l3fwd_em.c b/examples/l3fwd/l3fwd_em.c
index 9996bfba3..01f8dff48 100644
--- a/examples/l3fwd/l3fwd_em.c
+++ b/examples/l3fwd/l3fwd_em.c
@@ -629,8 +629,6 @@ em_main_loop(__rte_unused void *dummy)
 	const uint64_t drain_tsc = (rte_get_tsc_hz() + US_PER_S - 1) /
 		US_PER_S * BURST_TX_DRAIN_US;
 
-	prev_tsc = 0;
-
 	lcore_id = rte_lcore_id();
 	qconf = &lcore_conf[lcore_id];
 
@@ -650,9 +648,10 @@ em_main_loop(__rte_unused void *dummy)
 			lcore_id, portid, queueid);
 	}
 
-	while (!force_quit) {
+	cur_tsc = rte_rdtsc();
+	prev_tsc = cur_tsc;
 
-		cur_tsc = rte_rdtsc();
+	while (!force_quit) {
 
 		/*
 		 * TX burst queue drain
@@ -692,6 +691,8 @@ em_main_loop(__rte_unused void *dummy)
 							portid, qconf);
 #endif
 		}
+
+		cur_tsc = rte_rdtsc();
 	}
 
 	return 0;
diff --git a/examples/l3fwd/l3fwd_lpm.c b/examples/l3fwd/l3fwd_lpm.c
index 3dcf1fef1..375746fef 100644
--- a/examples/l3fwd/l3fwd_lpm.c
+++ b/examples/l3fwd/l3fwd_lpm.c
@@ -185,8 +185,6 @@ lpm_main_loop(__rte_unused void *dummy)
 	const uint64_t drain_tsc = (rte_get_tsc_hz() + US_PER_S - 1) /
 		US_PER_S * BURST_TX_DRAIN_US;
 
-	prev_tsc = 0;
-
 	lcore_id = rte_lcore_id();
 	qconf = &lcore_conf[lcore_id];
 
@@ -206,9 +204,10 @@ lpm_main_loop(__rte_unused void *dummy)
 			lcore_id, portid, queueid);
 	}
 
-	while (!force_quit) {
+	cur_tsc = rte_rdtsc();
+	prev_tsc = cur_tsc;
 
-		cur_tsc = rte_rdtsc();
+	while (!force_quit) {
 
 		/*
 		 * TX burst queue drain
@@ -249,6 +248,8 @@ lpm_main_loop(__rte_unused void *dummy)
 							portid, qconf);
 #endif /* X86 */
 		}
+
+		cur_tsc = rte_rdtsc();
 	}
 
 	return 0;
-- 
2.17.1