79 lines
3.6 KiB
Plaintext
79 lines
3.6 KiB
Plaintext
I have an IBM T420 running Ubuntu 24.04.
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The wifi acts weird: Over time it slows to a crawl, but if I
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disconnect and reconnect then the speed recovers to the expected
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speed.
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This is not a fluke: You might expect the wifi or my internet
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connection to be overloaded now and then, but this is reproducible.
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It sometime recover the speed by itself, but it is reproducible: Any
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time it is slow, simply reconnect wifi and the speed recovers.
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I did this `timeout 10 tcpdump -ni all` before and after reconnecting
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wifi.
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Note how the maximal time between packets is huge in the slow
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situation (number in ms since last packet):
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$ grep -v lo tcpdump.slow.txt |
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perl -pe 's/://g; s/^(\S+)/($1-$last)*1000/e;$last=$1;s/win.*//' |
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sort -n | head -n -1 | tail
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138.347000000067 wlp3s0 Out IP 192.168.100.133.53472 > 192.168.100.1.53 16660+ [1au] A? www.youtube.com. (44)
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143.536000003223 wlp3s0 In IP 91.189.91.42.443 > 192.168.100.133.41830 Flags [.], seq 3920040600, ack 1,
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145.438999999897 wlp3s0 In IP 172.217.145.198.443 > 192.168.100.133.33518 Flags [.], seq 217117218513, ack 4,
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161.396000010427 wlp3s0 In IP 91.189.91.42.443 > 192.168.100.133.41830 Flags [.], seq 1400015400, ack 1,
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163.872000004631 wlp3s0 In IP 172.217.145.198.443 > 192.168.100.133.33518 Flags [.], seq 9287394269, ack 4,
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209.784000006039 wlp3s0 In IP 172.217.145.198.443 > 192.168.100.133.33518 Flags [P.], seq 4401345409, ack 4,
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230.691000004299 wlp3s0 In IP 91.189.91.42.443 > 192.168.100.133.41830 Flags [.], seq 42949602964294961696, ack 1,
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239.476000002469 wlp3s0 In IP 172.217.145.198.443 > 192.168.100.133.33518 Flags [.], seq 2028121677, ack 4,
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244.7780000075 wlp3s0 In IP 91.189.91.42.443 > 192.168.100.133.41830 Flags [.], seq 1540016800, ack 1,
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453.129999994417 wlp3s0 In IP 91.189.91.42.443 > 192.168.100.133.41830 Flags [.], seq 23102893132310290713, ack 3045969685,
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But small in the fast situation:
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$ grep -v lo tcpdump.fast.txt |
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perl -pe 's/://g; s/^(\S+)/($1-$last)*1000/e;$last=$1;s/win.*//' |
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sort -n | head -n -1 | tail
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14.2179999966174 wlp3s0 In IP 122.2.214.142.443 > 192.168.100.133.48242 Flags [F.], seq 205202, ack 1933,
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14.4089999957941 wlp3s0 In IP 91.189.91.42.443 > 192.168.100.133.41830 Flags [.], seq 7000071400, ack 1,
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15.348000000813 wlp3s0 In IP 91.189.91.42.443 > 192.168.100.133.41830 Flags [.], seq 922600924000, ack 1,
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15.8539999974892 wlp3s0 In IP 122.2.214.142.443 > 192.168.100.133.48218 Flags [.], ack 1931,
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18.1480000028387 wlp3s0 In IP 202.138.160.143.443 > 192.168.100.133.58298 Flags [.], seq 131932133332, ack 1936,
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19.9160000047414 wlp3s0 In IP 122.2.214.142.443 > 192.168.100.133.48262 Flags [.], seq 3640537805, ack 1932,
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24.6269999915967 wlp3s0 In IP 91.189.91.42.443 > 192.168.100.133.41830 Flags [.], seq 1960021000, ack 1,
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29.4679999933578 wlp3s0 In IP 202.138.160.143.443 > 192.168.100.133.56522 Flags [F.], seq 5944, ack 1936,
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33.2009999983711 wlp3s0 In IP 202.138.160.143.443 > 192.168.100.133.56522 Flags [.], ack 1936,
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120.297000001301 wlp3s0 In IP 202.138.160.143.443 > 192.168.100.133.56522 Flags [P.], seq 42014531, ack 518,
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What causes this?
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https://git.data.coop/tange/Test/src/branch/main/slow-wifi
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dmesg.txt
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- dmesg entries when reconnecting wifi
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iwconfig.txt
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- ifconfig -a
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lspci.txt:
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- lscpi
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lsusb.txt
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- lsusb
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uname:
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- uname -a
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tcpdump.slow.txt:
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- Download big YouTube videos
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- Wait until wifi is slow
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- timeout 10 tcpdump -ni all
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- 884 packets
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tcpdump.fast.txt:
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- Continue downloading big YouTube videos
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- Disconnect and reconnect wifi (done immediately after slow)
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- timeout 10 tcpdump -ni all
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- 32029 packets
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