Change the unit of srtt and rto to usec, inspired by these in struct "tcp_info". Therefore, no need hz and tcp_rtt_scale in the headline of the log. Update the man page as well.

[cc]

Summary

Simplify srtt and rto values in siftr log.

Test Plan

Tested in Emulab testbed:
cc@s1:~ % sudo sysctl net.inet.siftr
net.inet.siftr.port_filter: 0
net.inet.siftr.genhashes: 0
net.inet.siftr.ppl: 1
net.inet.siftr.logfile: /var/log/siftr.log
net.inet.siftr.enabled: 0
cc@s1:~ % sudo sysctl net.inet.siftr.port_filter=5001
net.inet.siftr.port_filter: 0 -> 5001
cc@s1:~ % sudo sysctl net.inet.siftr.enabled=1
net.inet.siftr.enabled: 0 -> 1
cc@s1:~ %

cc@s1:~ % iperf -c r1 -n 1M

Client connecting to r1, TCP port 5001

TCP window size: 32.0 KByte (default)

[ 1] local 10.1.1.2 port 33817 connected with 10.1.1.3 port 5001
[ ID] Interval Transfer Bandwidth
[ 1] 0.00-0.91 sec 1.00 MBytes 9.22 Mbits/sec
cc@s1:~ % sudo sysctl net.inet.siftr.enabled=0
net.inet.siftr.enabled: 1 -> 0

cc@s1:~ % ll /var/log/siftr.log
-rw-r--r-- 1 root wheel 91K Apr 25 09:38 /var/log/siftr.log
cc@s1:~ % cat /var/log/siftr.log
enable_time_secs=1682437111 enable_time_usecs=121115 siftrver=1.3.0 sysname=FreeBSD sysver=1400088 ipmode=4
o,0x00000000,1682437125.907343,10.1.1.2,33817,10.1.1.3,5001,1073725440,1073725440,2,0,0,0,0,2,536,0,1,672,1000000,32768,0,65536,0,0,0,0,0
i,0x00000000,1682437126.106759,10.1.1.2,33817,10.1.1.3,5001,1073725440,1073725440,2,0,0,0,0,2,536,0,1,672,1000000,32768,0,65536,0,1,0,0,0
o,0x00000000,1682437126.106767,10.1.1.2,33817,10.1.1.3,5001,1073725440,14480,2,65535,65700,9,9,4,1460,201000,1,16778209,803000,33580,0,65700,0,0,0,0,0
o,0x00000000,1682437126.107141,10.1.1.2,33817,10.1.1.3,5001,1073725440,14480,2,65535,65700,9,9,4,1460,201000,1,16778208,803000,33580,60,65700,0,0,0,0,0
...
i,0x00000000,1682437127.016754,10.1.1.2,33817,10.1.1.3,5001,1073725440,606109,1030,748544,66048,9,9,9,1460,100812,1,1008,303000,475948,0,65700,0,0,0,0,0
o,0x00000000,1682437127.016759,10.1.1.2,33817,10.1.1.3,5001,1073725440,606109,1030,748544,66048,9,9,10,1460,100812,1,1011,303000,475948,0,65700,0,0,0,0,0
disable_time_secs=1682437131 disable_time_usecs=767582 num_inbound_tcp_pkts=371 num_outbound_tcp_pkts=186 total_tcp_pkts=557 num_inbound_skipped_pkts_malloc=0 num_outbound_skipped_pkts_malloc=0 num_inbound_skipped_pkts_tcpcb=0 num_outbound_skipped_pkts_tcpcb=0 num_inbound_skipped_pkts_inpcb=0 num_outbound_skipped_pkts_inpcb=0 total_skipped_tcp_pkts=0 flow_list=10.1.1.2;33817-10.1.1.3;5001,

[tuexen]

Isn't that another backwards incompatible change?

[cc]

In D39803#906274, @tuexen wrote:

Isn't that another backwards incompatible change?

:) On a second thought, I think we can stick to the recent version change for new changes, until the new branch is started, as most end users will use the release version of this.