我有一台 ubuntu 机器（Ubuntu 16.04.1 LTS）通过以太网连接到我的家庭路由器。我注意到通过 ssh 连接时性能很差，因此我从 ubuntu 机器运行了一些 ping 测试。它开始时很高，但以奇怪的一致速度下降。结果如下：
$ ping -c 30 www.google.com
PING www.google.com (216.58.217.164) 56(84) bytes of data.
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=1 ttl=56 time=99.7 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=2 ttl=56 time=98.1 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=3 ttl=56 time=97.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=4 ttl=56 time=96.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=5 ttl=56 time=95.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=6 ttl=56 time=94.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=7 ttl=56 time=93.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=8 ttl=56 time=92.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=9 ttl=56 time=91.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=10 ttl=56 time=89.9 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=11 ttl=56 time=88.9 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=12 ttl=56 time=87.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=13 ttl=56 time=86.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=14 ttl=56 time=85.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=15 ttl=56 time=84.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=16 ttl=56 time=83.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=17 ttl=56 time=82.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=18 ttl=56 time=81.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=19 ttl=56 time=80.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=20 ttl=56 time=79.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=21 ttl=56 time=78.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=22 ttl=56 time=77.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=23 ttl=56 time=76.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=24 ttl=56 time=75.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=25 ttl=56 time=74.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=26 ttl=56 time=73.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=27 ttl=56 time=72.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=28 ttl=56 time=71.0 ms
64 bytes from iad23s44-in-f164.1e100.net (216.58.217.164): icmp_seq=30 ttl=56 time=61.9 ms
和另一个要测试的网站
$ ping -c 30 www.apple.com
PING e6858.dsce9.akamaiedge.net (23.218.213.175) 56(84) bytes of data.
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=1 ttl=59 time=99.8 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=2 ttl=59 time=98.1 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=3 ttl=59 time=97.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=4 ttl=59 time=96.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=5 ttl=59 time=95.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=6 ttl=59 time=94.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=7 ttl=59 time=93.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=8 ttl=59 time=92.2 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=9 ttl=59 time=91.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=10 ttl=59 time=90.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=11 ttl=59 time=88.9 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=12 ttl=59 time=88.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=13 ttl=59 time=87.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=14 ttl=59 time=86.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=15 ttl=59 time=85.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=16 ttl=59 time=84.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=17 ttl=59 time=83.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=18 ttl=59 time=82.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=19 ttl=59 time=81.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=20 ttl=59 time=80.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=21 ttl=59 time=79.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=22 ttl=59 time=78.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=23 ttl=59 time=77.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=24 ttl=59 time=75.9 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=25 ttl=59 time=74.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=26 ttl=59 time=73.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=27 ttl=59 time=72.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=28 ttl=59 time=71.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=29 ttl=59 time=70.0 ms
64 bytes from a23-218-213-175.deploy.static.akamaitechnologies.com (23.218.213.175): icmp_seq=30 ttl=59 time=69.0 ms
有人知道什么可能会导致这种行为吗？
更新：
对路由器执行 Ping 操作会得到同样的结果，因此问题肯定出在本地网络上。无论如何，这是来自地铁的报告：
Loss% Snt Last Avg Best Wrst StDev
1.|-- 192.168.1.1 0.0% 10 74.6 81.9 74.6 100.0 9.1
2.|-- lo0-100.WASHDC-VFTTP-311.verizon-gni.net 0.0% 10 74.6 72.7 8.9 97.4 23.3
3.|-- B3311.WASHDC-LCR-22.verizon-gni.net 0.0% 10 74.5 73.6 17.9 97.3 20.6
4.|-- ??? 100.0 10 0.0 0.0 0.0 0.0 0.0
5.|-- ??? 100.0 10 0.0 0.0 0.0 0.0 0.0
6.|-- 0.et-10-3-0.GW13.IAD8.ALTER.NET 0.0% 10 74.2 76.0 44.8 97.0 12.7
7.|-- 204.148.79.46 10.0% 10 74.1 76.7 53.8 96.9 11.0
8.|-- 209.85.252.121 0.0% 10 74.1 77.6 62.9 96.8 8.3
9.|-- 209.85.143.145 10.0% 10 74.0 78.4 71.9 96.8 7.3
10.|-- iad23s44-in-f164.1e100.net 10.0% 10 73.9 79.2 73.9 96.7 6.9
不知道4和5是什么。
$tc qdisc
qdisc noqueue 0: dev lo root refcnt 2
qdisc pfifo_fast 0: dev enp9s0 root refcnt 2 bands 3 priomap 1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1