| Demonstrations of tcprtt, the Linux eBPF/bcc version. |
| |
| |
| This program traces TCP RTT(round-trip time) to analyze the quality of |
| network, then help us to distinguish the network latency trouble is from |
| user process or physical network. |
| |
| For example, wrk show the http request latency distribution: |
| # wrk -d 30 -c 10 --latency http://192.168.122.100/index.html |
| Running 30s test @ http://192.168.122.100/index.html |
| 2 threads and 10 connections |
| Thread Stats Avg Stdev Max +/- Stdev |
| Latency 86.75ms 153.76ms 1.54s 90.85% |
| Req/Sec 160.91 76.07 424.00 67.06% |
| Latency Distribution |
| 50% 14.55ms |
| 75% 119.21ms |
| 90% 230.22ms |
| 99% 726.90ms |
| 9523 requests in 30.02s, 69.62MB read |
| Socket errors: connect 0, read 0, write 0, timeout 1 |
| |
| During wrk testing, run tcprtt: |
| # ./tcprtt -i 1 -d 10 -m |
| Tracing TCP RTT... Hit Ctrl-C to end. |
| msecs : count distribution |
| 0 -> 1 : 4 | | |
| 2 -> 3 : 0 | | |
| 4 -> 7 : 1055 |****************************************| |
| 8 -> 15 : 26 | | |
| 16 -> 31 : 0 | | |
| 32 -> 63 : 0 | | |
| 64 -> 127 : 18 | | |
| 128 -> 255 : 14 | | |
| 256 -> 511 : 14 | | |
| 512 -> 1023 : 12 | | |
| |
| The wrk output shows that the latency of web service is not stable, and tcprtt |
| also shows unstable TCP RTT. So in this situation, we need to make sure the |
| quality of network is good or not firstly. |
| |
| |
| Use filter for address and(or) port. Ex, only collect local address 192.168.122.200 |
| and remote address 192.168.122.100 and remote port 80. |
| # ./tcprtt -i 1 -d 10 -m -a 192.168.122.200 -A 192.168.122.100 -P 80 |
| |
| |
| Tracing at server side, show each clients with its own histogram. |
| For example, run tcprtt on a storage node to show initiators' rtt histogram: |
| # ./tcprtt -i 1 --lport 3260 --byraddr -e |
| Tracing TCP RTT... Hit Ctrl-C to end. |
| |
| |
| Remote Addres = 10.194.87.206 [AVG 170] |
| usecs : count distribution |
| 0 -> 1 : 0 | | |
| 2 -> 3 : 0 | | |
| 4 -> 7 : 0 | | |
| 8 -> 15 : 0 | | |
| 16 -> 31 : 0 | | |
| 32 -> 63 : 31 | | |
| 64 -> 127 : 5150 |******************* | |
| 128 -> 255 : 10327 |****************************************| |
| 256 -> 511 : 1014 |*** | |
| 512 -> 1023 : 10 | | |
| 1024 -> 2047 : 7 | | |
| 2048 -> 4095 : 14 | | |
| 4096 -> 8191 : 10 | | |
| |
| Remote Addres = 10.194.87.197 [AVG 4293] |
| usecs : count distribution |
| 0 -> 1 : 0 | | |
| 2 -> 3 : 0 | | |
| 4 -> 7 : 0 | | |
| 8 -> 15 : 0 | | |
| 16 -> 31 : 0 | | |
| 32 -> 63 : 0 | | |
| 64 -> 127 : 0 | | |
| 128 -> 255 : 0 | | |
| 256 -> 511 : 0 | | |
| 512 -> 1023 : 0 | | |
| 1024 -> 2047 : 3 |******** | |
| 2048 -> 4095 : 12 |********************************** | |
| 4096 -> 8191 : 14 |****************************************| |
| |
| Remote Addres = 10.194.88.148 [AVG 6215] |
| usecs : count distribution |
| 0 -> 1 : 0 | | |
| 2 -> 3 : 0 | | |
| 4 -> 7 : 0 | | |
| 8 -> 15 : 0 | | |
| 16 -> 31 : 0 | | |
| 32 -> 63 : 0 | | |
| 64 -> 127 : 0 | | |
| 128 -> 255 : 0 | | |
| 256 -> 511 : 0 | | |
| 512 -> 1023 : 0 | | |
| 1024 -> 2047 : 0 | | |
| 2048 -> 4095 : 0 | | |
| 4096 -> 8191 : 2 |****************************************| |
| |
| Remote Addres = 10.194.87.90 [AVG 2188] |
| usecs : count distribution |
| 0 -> 1 : 0 | | |
| 2 -> 3 : 0 | | |
| 4 -> 7 : 0 | | |
| 8 -> 15 : 0 | | |
| 16 -> 31 : 0 | | |
| 32 -> 63 : 0 | | |
| 64 -> 127 : 0 | | |
| 128 -> 255 : 0 | | |
| 256 -> 511 : 15 |********* | |
| 512 -> 1023 : 30 |****************** | |
| 1024 -> 2047 : 50 |****************************** | |
| 2048 -> 4095 : 65 |****************************************| |
| 4096 -> 8191 : 22 |************* | |
| |
| .... |
| |
| |
| Use -e(--extension) to show extension RTT: |
| # ./tcprtt -i 1 -e |
| |
| All Addresses = ******* [AVG 324] |
| usecs : count distribution |
| 0 -> 1 : 0 | | |
| 2 -> 3 : 0 | | |
| 4 -> 7 : 0 | | |
| 8 -> 15 : 0 | | |
| 16 -> 31 : 0 | | |
| 32 -> 63 : 0 | | |
| 64 -> 127 : 5360 |******** | |
| 128 -> 255 : 23834 |****************************************| |
| 256 -> 511 : 11276 |****************** | |
| 512 -> 1023 : 700 |* | |
| 1024 -> 2047 : 434 | | |
| 2048 -> 4095 : 356 | | |
| 4096 -> 8191 : 328 | | |
| 8192 -> 16383 : 91 | | |
| |
| |
| Full USAGE: |
| |
| # ./tcprtt -h |
| usage: tcprtt [-h] [-i INTERVAL] [-d DURATION] [-T] [-m] [-p LPORT] |
| [-P RPORT] [-a LADDR] [-A RADDR] [-b] [-B] [-e] [-D] |
| [-4 | -6] |
| |
| Summarize TCP RTT as a histogram |
| |
| optional arguments: |
| -h, --help show this help message and exit |
| -i INTERVAL, --interval INTERVAL |
| summary interval, seconds |
| -d DURATION, --duration DURATION |
| total duration of trace, seconds |
| -T, --timestamp include timestamp on output |
| -m, --milliseconds millisecond histogram |
| -p LPORT, --lport LPORT |
| filter for local port |
| -P RPORT, --rport RPORT |
| filter for remote port |
| -a LADDR, --laddr LADDR |
| filter for local address |
| -A RADDR, --raddr RADDR |
| filter for remote address |
| -b, --byladdr show sockets histogram by local address |
| -B, --byraddr show sockets histogram by remote address |
| -e, --extension show extension summary(average) |
| -D, --debug print BPF program before starting (for debugging |
| purposes) |
| -4, --ipv4 trace IPv4 family only |
| -6, --ipv6 trace IPv6 family only |
| |
| examples: |
| ./tcprtt # summarize TCP RTT |
| ./tcprtt -i 1 -d 10 # print 1 second summaries, 10 times |
| ./tcprtt -m -T # summarize in millisecond, and timestamps |
| ./tcprtt -p # filter for local port |
| ./tcprtt -P # filter for remote port |
| ./tcprtt -a # filter for local address |
| ./tcprtt -A # filter for remote address |
| ./tcprtt -b # show sockets histogram by local address |
| ./tcprtt -B # show sockets histogram by remote address |
| ./tcprtt -D # show debug bpf text |
| ./tcprtt -e # show extension summary(average) |
| ./tcprtt -4 # trace IPv4 family only |
| ./tcprtt -6 # trace IPv6 family only |
