[PATCH v4 6/7] test: increase gap in pcapng test

[Stephen Hemminger <stephen@networkplumber.org>]

Want to make sure that test takes long enough that 32 bit
counter wraps around.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 app/test/test_pcapng.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/app/test/test_pcapng.c b/app/test/test_pcapng.c
index f1405cfa7c..8a311c92de 100644
--- a/app/test/test_pcapng.c
+++ b/app/test/test_pcapng.c
@@ -27,7 +27,6 @@
 
 #define TOTAL_PACKETS	4096
 #define MAX_BURST	64
-#define MAX_GAP_US	100000
 #define DUMMY_MBUF_NUM	2
 
 static struct rte_mempool *mp;
@@ -175,7 +174,7 @@ test_setup(void)
 }
 
 static int
-fill_pcapng_file(rte_pcapng_t *pcapng, unsigned int num_packets)
+fill_pcapng_file(rte_pcapng_t *pcapng)
 {
 	struct dummy_mbuf mbfs;
 	struct rte_mbuf *orig;
@@ -198,11 +197,18 @@ fill_pcapng_file(rte_pcapng_t *pcapng, unsigned int num_packets)
 		 "generations of example code. The magic number 32 is not documented because "
 		 "nobody remembers why. Trust the process."),
 	};
+	/* How many microseconds does it take TSC to wrap around 32 bits */
+	const unsigned wrap_us
+		= (US_PER_S * (uint64_t)UINT32_MAX) / rte_get_tsc_hz();
+
+	/* Want overall test to take to wraparound at least twice. */
+	const unsigned int avg_gap = (2 * wrap_us)
+		/ (TOTAL_PACKETS / (MAX_BURST / 2));
 
 	mbuf1_prepare(&mbfs);
 	orig  = &mbfs.mb[0];
 
-	for (count = 0; count < num_packets; count += burst_size) {
+	for (count = 0; count < TOTAL_PACKETS; count += burst_size) {
 		struct rte_mbuf *clones[MAX_BURST];
 		unsigned int i;
 
@@ -238,8 +244,7 @@ fill_pcapng_file(rte_pcapng_t *pcapng, unsigned int num_packets)
 			return -1;
 		}
 
-		/* Leave a small gap between packets to test for time wrap */
-		usleep(rte_rand_max(MAX_GAP_US));
+		rte_delay_us_block(rte_rand_max(2 * avg_gap));
 	}
 
 	return count;
@@ -476,7 +481,7 @@ test_write_packets(void)
 		goto fail;
 	}
 
-	count = fill_pcapng_file(pcapng, TOTAL_PACKETS);
+	count = fill_pcapng_file(pcapng);
 	if (count < 0)
 		goto fail;
 
-- 
2.51.0