slow-wifi: dmesg

slow-wifi/README.txt

@@ -1,3 +1,58 @@
+I have an IBM T420 running Ubuntu 24.04.
+
+The wifi acts weird: Over time it slows to a crawl, but if I
+disconnect and reconnect then the speed recovers to the expected
+speed.
+
+This is not a fluke: You might expect the wifi or my internet
+connection to be overloaded now and then, but this is reproducible.
+
+It sometime recover the speed by itself, but it is reproducible: Any
+time it is slow, simply reconnect wifi and the speed recovers.
+
+I did this `timeout 10 tcpdump -ni all` before and after reconnecting
+wifi.
+
+Note how the maximal time between packets is huge in the slow
+situation (number in ms since last packet):
+
+    $ grep -v lo tcpdump.slow.txt |
+        perl -pe 's/://g; s/^(\S+)/($1-$last)*1000/e;$last=$1;s/win.*//' |
+	sort -n | head -n -1 | tail
+    138.347000000067 wlp3s0 Out IP 192.168.100.133.53472 > 192.168.100.1.53 16660+ [1au] A? www.youtube.com. (44)
+    143.536000003223 wlp3s0 In  IP 91.189.91.42.443 > 192.168.100.133.41830 Flags [.], seq 3920040600, ack 1, 
+    145.438999999897 wlp3s0 In  IP 172.217.145.198.443 > 192.168.100.133.33518 Flags [.], seq 217117218513, ack 4, 
+    161.396000010427 wlp3s0 In  IP 91.189.91.42.443 > 192.168.100.133.41830 Flags [.], seq 1400015400, ack 1, 
+    163.872000004631 wlp3s0 In  IP 172.217.145.198.443 > 192.168.100.133.33518 Flags [.], seq 9287394269, ack 4, 
+    209.784000006039 wlp3s0 In  IP 172.217.145.198.443 > 192.168.100.133.33518 Flags [P.], seq 4401345409, ack 4, 
+    230.691000004299 wlp3s0 In  IP 91.189.91.42.443 > 192.168.100.133.41830 Flags [.], seq 42949602964294961696, ack 1, 
+    239.476000002469 wlp3s0 In  IP 172.217.145.198.443 > 192.168.100.133.33518 Flags [.], seq 2028121677, ack 4, 
+    244.7780000075 wlp3s0 In  IP 91.189.91.42.443 > 192.168.100.133.41830 Flags [.], seq 1540016800, ack 1, 
+    453.129999994417 wlp3s0 In  IP 91.189.91.42.443 > 192.168.100.133.41830 Flags [.], seq 23102893132310290713, ack 3045969685, 
+
+But small in the fast situation:
+
+    $ grep -v lo tcpdump.fast.txt |
+        perl -pe 's/://g; s/^(\S+)/($1-$last)*1000/e;$last=$1;s/win.*//' |
+	sort -n | head -n -1 | tail
+    14.2179999966174 wlp3s0 In  IP 122.2.214.142.443 > 192.168.100.133.48242 Flags [F.], seq 205202, ack 1933, 
+    14.4089999957941 wlp3s0 In  IP 91.189.91.42.443 > 192.168.100.133.41830 Flags [.], seq 7000071400, ack 1, 
+    15.348000000813 wlp3s0 In  IP 91.189.91.42.443 > 192.168.100.133.41830 Flags [.], seq 922600924000, ack 1, 
+    15.8539999974892 wlp3s0 In  IP 122.2.214.142.443 > 192.168.100.133.48218 Flags [.], ack 1931, 
+    18.1480000028387 wlp3s0 In  IP 202.138.160.143.443 > 192.168.100.133.58298 Flags [.], seq 131932133332, ack 1936, 
+    19.9160000047414 wlp3s0 In  IP 122.2.214.142.443 > 192.168.100.133.48262 Flags [.], seq 3640537805, ack 1932, 
+    24.6269999915967 wlp3s0 In  IP 91.189.91.42.443 > 192.168.100.133.41830 Flags [.], seq 1960021000, ack 1, 
+    29.4679999933578 wlp3s0 In  IP 202.138.160.143.443 > 192.168.100.133.56522 Flags [F.], seq 5944, ack 1936, 
+    33.2009999983711 wlp3s0 In  IP 202.138.160.143.443 > 192.168.100.133.56522 Flags [.], ack 1936, 
+    120.297000001301 wlp3s0 In  IP 202.138.160.143.443 > 192.168.100.133.56522 Flags [P.], seq 42014531, ack 518, 
+
+What causes this?
+
+https://git.data.coop/tange/Test/src/branch/main/slow-wifi
+
+dmesg.txt
+- dmesg entries when reconnecting wifi
+
 iwconfig.txt
 - ifconfig -a
 
@@ -11,9 +66,13 @@ uname:
 - uname -a
 
 tcpdump.slow.txt:
+- Download big YouTube videos
 - Wait until wifi is slow
 - timeout 10 tcpdump -ni all 
+- 884 packets
 
 tcpdump.fast.txt:
+- Continue downloading big YouTube videos
 - Disconnect and reconnect wifi (done immediately after slow)
 - timeout 10 tcpdump -ni all 
+- 32029 packets

slow-wifi/dmesg.txt

@@ -0,0 +1,13 @@
+Disconnect wifi:
+
+[133788.817139] wlp3s0: deauthenticating from 44:e9:68:6b:5a:4c by local choice (Reason: 3=DEAUTH_LEAVING)
+
+Reconnect wifi:
+
+[133797.689225] wlp3s0: authenticate with 44:e9:68:6b:5a:4c (local address=8c:a9:82:92:77:90)
+[133797.689234] wlp3s0: send auth to 44:e9:68:6b:5a:4c (try 1/3)
+[133797.794490] wlp3s0: send auth to 44:e9:68:6b:5a:4c (try 2/3)
+[133797.799043] wlp3s0: authenticated
+[133797.800483] wlp3s0: associate with 44:e9:68:6b:5a:4c (try 1/3)
+[133797.804761] wlp3s0: RX AssocResp from 44:e9:68:6b:5a:4c (capab=0x1431 status=0 aid=85)
+[133797.809892] wlp3s0: associated