As of this morning my LXDE keyboard input is unbelievably laggy. I have to very carefully type one character at the time and it can take several seconds for the glyph to appear onscreen. Sometimes I get repeats and sometimes they repeat endlessly. Everything else appears normal. The system is under no strain at all, has 8GB of RAM and the problem occurs with all applications tried so far (Chrome, Thunderbird, LibreOffice Writer, LXTerminal...) even when loaded one at the time. The problem persists across boots (indeed is worst right after login). The login manager (password entry screen) does not seem to suffer from the same problem. I made no modification to my system prior to the problem arising yesterday but this morning I executed an apt-get update && apt-get upgrade cycle to see if that might rectify matters. Yesterday I had been testing Hibernation (to no avail) when the problem first arose, leading me to believe that the issue was related to VM and swap, but I am increasingly convinced the matter is largely coincidental (maybe I do indeed lack a swap partition, but it should hardly be an issue on a fast, modern machine with oodles of RAM after a fresh reboot). Somebody mentioned stray NFS as a possible source of resource depletion but I am sceptical as I do not have any NFS exports enabled as far as I am aware. Disconnecting the machine from WiFi did not lessen the problem, so in practical terms I doubt it is a network-related issue. As far as I can see I have no runaway processes burning resources, but here is the current output of my top list just in somebody can spot something I am missing.
Tasks: 195 total, 3 running, 192 sleeping, 0 stopped, 0 zombie
%Cpu(s): 0.4 us, 0.3 sy, 0.0 ni, 99.3 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem: 7689472 total, 1415268 used, 6274204 free, 48268 buffers
KiB Swap: 0 total, 0 used, 0 free. 621716 cached Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
2265 user 20 0 856168 17980 11016 S 0.7 0.2 0:00.78 lxterminal
1402 root 20 0 279148 46736 38736 S 0.3 0.6 0:11.10 Xorg
2584 user 20 0 29192 1740 1220 R 0.3 0.0 0:02.49 top
1 root 20 0 34176 3492 1484 S 0.0 0.0 0:03.75 init
2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd
3 root 20 0 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/0
5 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/0:0H
7 root 20 0 0 0 0 R 0.0 0.0 0:00.37 rcu_sched
8 root 20 0 0 0 0 S 0.0 0.0 0:00.12 rcuos/0
9 root 20 0 0 0 0 S 0.0 0.0 0:00.12 rcuos/1
10 root 20 0 0 0 0 S 0.0 0.0 0:00.15 rcuos/2
11 root 20 0 0 0 0 S 0.0 0.0 0:00.12 rcuos/3
12 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcuos/4
13 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcuos/5
14 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcuos/6
15 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcuos/7
16 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcu_bh
17 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcuob/0
18 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcuob/1
19 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcuob/2
20 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcuob/3
21 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcuob/4
22 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcuob/5
23 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcuob/6
24 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcuob/7
25 root rt 0 0 0 0 S 0.0 0.0 0:00.62 migration/0
28 root rt 0 0 0 0 S 0.0 0.0 0:01.14 migration/1
29 root 20 0 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/1
30 root 20 0 0 0 0 S 0.0 0.0 0:00.56 kworker/1:0
31 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/1:0H
33 root rt 0 0 0 0 S 0.0 0.0 0:01.39 migration/2
34 root 20 0 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/2
36 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/2:0H
38 root rt 0 0 0 0 S 0.0 0.0 0:00.09 migration/3
39 root 20 0 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/3
41 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/3:0H
42 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 khelper
43 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kdevtmpfs
44 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 netns
45 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 writeback
46 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kintegrityd
47 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 bioset
48 root 0 -20 0 0 0 S 0.0 0.0 0:00.01 kworker/u17:0
49 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kblockd
50 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 ata_sff
51 root 20 0 0 0 0 S 0.0 0.0 0:00.00 khubd
52 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 md
53 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 devfreq_wq
55 root 20 0 0 0 0 S 0.0 0.0 0:00.78 kworker/0:1
61 root 20 0 0 0 0 S 0.0 0.0 0:00.00 khungtaskd
62 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kswapd0
63 root 25 5 0 0 0 S 0.0 0.0 0:00.00 ksmd
At present the system is totally unusable and since I need to get it back into working order in time for a business trip on Thursday if I do not find a solution to this (likely trivial) issue I shall be, sadly, forced to totally reinstall in order to circumvent the issue. That of course would be a crying shame but being a total novice I lack the means to identify the problem.
