[dpdk-dev] [RFC] [PATCH v1 3/3] net/pcap: dump hardware timestamps

[Patrick Keroulas <patrick.keroulas@radio-canada.ca>]

When hardware timestamping is activated, system time should no longer be
used to timestamp dumped the packets. Instead, use value held by
forwarded and assume they were converted to nanoseconds.

Signed-off-by: Patrick Keroulas <patrick.keroulas@radio-canada.ca>
Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
---
 drivers/net/pcap/rte_eth_pcap.c | 32 ++++++++++++++++++++++----------
 1 file changed, 22 insertions(+), 10 deletions(-)

diff --git a/drivers/net/pcap/rte_eth_pcap.c b/drivers/net/pcap/rte_eth_pcap.c
index b4c79d174..1303e3338 100644
--- a/drivers/net/pcap/rte_eth_pcap.c
+++ b/drivers/net/pcap/rte_eth_pcap.c
@@ -45,6 +45,8 @@
 
 #define RTE_PMD_PCAP_MAX_QUEUES 16
 
+#define NSEC_PER_SEC	1000000000L
+
 static char errbuf[PCAP_ERRBUF_SIZE];
 static struct timeval start_time;
 static uint64_t start_cycles;
@@ -288,14 +290,24 @@ eth_null_rx(void *queue __rte_unused,
 }
 
 static inline void
-calculate_timestamp(struct timeval *ts) {
-	uint64_t cycles;
-	struct timeval cur_time;
-
-	cycles = rte_get_timer_cycles() - start_cycles;
-	cur_time.tv_sec = cycles / hz;
-	cur_time.tv_usec = (cycles % hz) * 1e6 / hz;
-	timeradd(&start_time, &cur_time, ts);
+calculate_timestamp(const struct rte_mbuf *mbuf, struct timeval *ts) {
+	if (mbuf->ol_flags & PKT_RX_TIMESTAMP) {
+		/* timestamp unit is nanoseconds but must fit in timeval */
+		ts->tv_sec = mbuf->timestamp / NSEC_PER_SEC;
+		ts->tv_usec = mbuf->timestamp % NSEC_PER_SEC;
+	}
+	else {
+		uint64_t cycles = rte_get_timer_cycles() - start_cycles;
+		struct timeval cur_time;
+		cur_time.tv_sec = cycles / hz;
+		cur_time.tv_usec = (cycles % hz) * NSEC_PER_SEC / hz;
+		ts->tv_sec = start_time.tv_sec + cur_time.tv_sec;
+		ts->tv_usec = start_time.tv_usec + cur_time.tv_usec;
+		if (ts->tv_usec > NSEC_PER_SEC) {
+			ts->tv_usec -= NSEC_PER_SEC;
+			ts->tv_sec += 1;
+		}
+	}
 }
 
 /*
@@ -331,7 +343,7 @@ eth_pcap_tx_dumper(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
 			caplen = sizeof(temp_data);
 		}
 
-		calculate_timestamp(&header.ts);
+		calculate_timestamp(mbuf, &header.ts);
 		header.len = len;
 		header.caplen = caplen;
 		/* rte_pktmbuf_read() returns a pointer to the data directly
@@ -475,7 +487,7 @@ open_single_tx_pcap(const char *pcap_filename, pcap_dumper_t **dumper)
 	 * with pcap_dump_open(). We create big enough an Ethernet
 	 * pcap holder.
 	 */
-	tx_pcap = pcap_open_dead(DLT_EN10MB, RTE_ETH_PCAP_SNAPSHOT_LEN);
+	tx_pcap = pcap_open_dead_with_tstamp_precision(DLT_EN10MB, RTE_ETH_PCAP_SNAPSHOT_LEN, PCAP_TSTAMP_PRECISION_NANO);
 	if (tx_pcap == NULL) {
 		PMD_LOG(ERR, "Couldn't create dead pcap");
 		return -1;
-- 
2.17.1