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Good breakdown of printing timing breakdown of curl. For example command:
curl -L --output /dev/null --silent --show-error --write-out 'lookup: %{time_namelookup}\nconnect: %{time_connect}\nappconnect: %{time_appconnect}\npretransfer: %{time_pretransfer}\nredirect: %{time_redirect}\nstarttransfer: %{time_starttransfer}\ntotal: %{time_total}\n' 'https://google.com'
lookup: 0.038
connect: 0.063
appconnect: 0.177
pretransfer: 0.178
redirect: 0.225
starttransfer: 0.679
total: 0.929
From the man pages -
lookup: The time, in seconds, it took from the start until the name resolving was completed.
connect: The time, in seconds, it took from the start until the TCP connect to the remote host (or proxy) was completed.
appconnect: The time, in seconds, it took from the start until the SSL/SSH/etc connect/handshake to the remote host was completed. (Added in 7.19.0)
pretransfer: The time, in seconds, it took from the start until the file transfer was just about to begin. This includes all pre-transfer commands and negotiations that are specific to the particular protocol(s) involved.
redirect: The time, in seconds, it took for all redirection steps include name lookup, connect, pretransfer and transfer before the final transaction was started. time_redirect shows the complete execution time for multiple redirections. (Added in 7.12.3)
starttransfer: The time, in seconds, it took from the start until the first byte was just about to be transferred. This includes time_pretransfer and also the time the server needed to calculate the result.
total: The total time, in seconds, that the full operation lasted. The time will be displayed with millisecond resolution.
curl -L --output /dev/null --silent --show-error --write-out 'lookup: %{time_namelookup}\nconnect: %{time_connect}\nappconnect: %{time_appconnect}\npretransfer: %{time_pretransfer}\nredirect: %{time_redirect}\nstarttransfer: %{time_starttransfer}\ntotal: %{time_total}\n' 'https://google.com'
lookup: 0.038
connect: 0.063
appconnect: 0.177
pretransfer: 0.178
redirect: 0.225
starttransfer: 0.679
total: 0.929
From the man pages -
lookup: The time, in seconds, it took from the start until the name resolving was completed.
connect: The time, in seconds, it took from the start until the TCP connect to the remote host (or proxy) was completed.
appconnect: The time, in seconds, it took from the start until the SSL/SSH/etc connect/handshake to the remote host was completed. (Added in 7.19.0)
pretransfer: The time, in seconds, it took from the start until the file transfer was just about to begin. This includes all pre-transfer commands and negotiations that are specific to the particular protocol(s) involved.
redirect: The time, in seconds, it took for all redirection steps include name lookup, connect, pretransfer and transfer before the final transaction was started. time_redirect shows the complete execution time for multiple redirections. (Added in 7.12.3)
starttransfer: The time, in seconds, it took from the start until the first byte was just about to be transferred. This includes time_pretransfer and also the time the server needed to calculate the result.
total: The total time, in seconds, that the full operation lasted. The time will be displayed with millisecond resolution.
Host Anycast Service
tcp slow start fast retransmission's congestion duplicate acknowledgements
Setting Max Segment Size (MSS) via iptables
# Add rules
$ sudo iptables -I OUTPUT -p tcp -m tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss 48
# delete rules
$ sudo iptables -D OUTPUT -p tcp -m tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss 48
# Add rules
$ sudo iptables -I OUTPUT -p tcp -m tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss 48
# delete rules
$ sudo iptables -D OUTPUT -p tcp -m tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss 48
weird MTU in wireshark - result of TCP segmentation offload