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net/pcap: support Tx nanosecond timestamps

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When capturing packets into a PCAP file, DPDK currently uses
microseconds for the timestamps. But libpcap supports interpreting
tv_usec as nanoseconds depending on the file timestamp precision,
as of commit ba89e4a18e8b ("Make timestamps precision configurable").

To support this, use PCAP_TSTAMP_PRECISION_NANO when creating the
empty PCAP file as specified by PCAP_OPEN_DEAD(3PCAP) and implement
nanosecond timeval addition. This also ensures that the precision
reported by capinfos is nanoseconds (9).

Note that NSEC_PER_SEC is defined as 1000000000L instead of 1e9 since
the latter might be interpreted as floating point.

Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Acked-by: Ferruh Yigit <ferruh.yigit@intel.com>
This commit is contained in:
Vivien Didelot 2020-06-09 15:07:19 -04:00 committed by Ferruh Yigit
parent 3efac8085e
commit a7d42145cc
2 changed files with 18 additions and 3 deletions
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6
doc/guides/rel_notes/release_20_08.rst
View File

@ -56,6 +56,12 @@ New Features
Also, make sure to start the actual text at the margin.
=========================================================
* **Updated PCAP driver.**
Updated PCAP driver with new features and improvements, including:
* Support software Tx nanosecond timestamps precision.
* **Updated Mellanox mlx5 driver.**
Updated Mellanox mlx5 driver with new features and improvements, including:

15
drivers/net/pcap/rte_eth_pcap.c
View File

@ -287,6 +287,8 @@ eth_null_rx(void *queue __rte_unused,
return 0;
}
#define NSEC_PER_SEC 1000000000L
static inline void
calculate_timestamp(struct timeval *ts) {
uint64_t cycles;
@ -294,8 +296,14 @@ calculate_timestamp(struct timeval *ts) {
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);
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;
}
}
/*
@ -475,7 +483,8 @@ 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;