[dpdk-dev] [PATCH] net/pcap: support hardware Tx timestamps

Vivien Didelot vivien.didelot at gmail.com
Wed Jun 10 21:39:38 CEST 2020


When hardware timestamping is enabled on Rx path, system time should
no longer be used to calculate the timestamps when dumping packets.

Instead, use the value stored by the driver in mbuf->timestamp
and assume it is already converted to nanoseconds (otherwise the
application may edit the packet headers itself afterwards).

Signed-off-by: Vivien Didelot <vivien.didelot at gmail.com>
Signed-off-by: Patrick Keroulas <patrick.keroulas at radio-canada.ca>
---
 doc/guides/rel_notes/release_20_08.rst |  1 +
 drivers/net/pcap/rte_eth_pcap.c        | 30 +++++++++++++++-----------
 2 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/doc/guides/rel_notes/release_20_08.rst b/doc/guides/rel_notes/release_20_08.rst
index 7a67c960c..cedceaf9d 100644
--- a/doc/guides/rel_notes/release_20_08.rst
+++ b/doc/guides/rel_notes/release_20_08.rst
@@ -61,6 +61,7 @@ New Features
   Updated PCAP driver with new features and improvements, including:
 
   * Support software Tx nanosecond timestamps precision.
+  * Support hardware Tx timestamps.
 
 * **Updated Mellanox mlx5 driver.**
 
diff --git a/drivers/net/pcap/rte_eth_pcap.c b/drivers/net/pcap/rte_eth_pcap.c
index 13a3d0ac7..3d80b699b 100644
--- a/drivers/net/pcap/rte_eth_pcap.c
+++ b/drivers/net/pcap/rte_eth_pcap.c
@@ -290,19 +290,23 @@ eth_null_rx(void *queue __rte_unused,
 #define NSEC_PER_SEC	1000000000L
 
 static inline void
-calculate_timestamp(struct timeval *ts) {
-	uint64_t cycles;
-	struct timeval cur_time;
+calculate_timestamp(const struct rte_mbuf *mbuf, struct timeval *ts) {
+	if (mbuf->ol_flags & PKT_RX_TIMESTAMP) {
+		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 = {
+			.tv_sec = cycles / hz,
+			.tv_usec = (cycles % hz) * NSEC_PER_SEC / hz,
+		};
 
-	cycles = rte_get_timer_cycles() - start_cycles;
-	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;
+		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;
+		}
 	}
 }
 
@@ -339,7 +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
-- 
2.27.0



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