I'm running Ubuntu 13.10 on a laptop.  Recently, after waking from sleep, I noticed the computer was quite warm, checked top and discovered 1.00 load average.  I shutdown Chrome, various daemons, no effect.I rebooted and fired up a terminal and checked top again, and watched the load quickly spike to 1.75, and slowly settle down back to around 1.0 - 1.2:top - 09:49:17 up 36 min,  2 users,  load average: 1.01, 1.10, 1.01Tasks: 267 total,   1 running, 266 sleeping,   0 stopped,   0 zombie%Cpu(s):  0.9 us,  0.4 sy,  0.0 ni, 98.6 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 stKiB Mem:   8069288 total,  2885572 used,  5183716 free,   123652 buffersKiB Swap:  7711332 total,        0 used,  7711332 free,  1661816 cached  PID USER      PR  NI  VIRT  RES  SHR S  %CPU %MEM    TIME+  COMMAND                                                                                                                                         1420 root      20   0  589m 144m 131m S   3.4  1.8   0:36.49 Xorg                                                                                                                                            6233 user1    20   0  986m  83m  31m S   2.7  1.1   0:19.89 chrome                                                                                                                                          3708 user1    20   0  749m  19m  12m S   1.8  0.3   0:06.58 gnome-terminal                                                                                                                                  3526 user1    20   0 1350m  67m  28m S   1.4  0.9   0:26.19 compiz                                                                                                                                          4014 user1    20   0 1022m 126m  52m S   1.1  1.6   0:44.34 chrome                                                                                                                                         I checked /proc/loadavg manually, same story:sudo cat /proc/loadavg1.20 1.16 0.99 3/614 6254ps auxwwwf doesn't show any process consuming more than 6.0% of CPU.iostat:avg-cpu:  %user   %nice %system %iowait  %steal   %idle           0.63    0.00    0.13    0.00    0.00   99.25Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %utilsda               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00scd0              0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00free -m:             total       used       free     shared    buffers     cachedMem:          7880       2841       5039          0        120       1651-/+ buffers/cache:       1068       6811Swap:         7530          0       7530Clearly some process is saturating CPU, but it doesn't seem to show up on the process list.  Some sort of hidden Linux filesystem checker?  Rootkit?  Any ideas how to find the process in question?
How to troubleshoot high load, when there are no obvious processes
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Load average doesn't mean what you think it means. It's not about instant CPU usage, but rather how many processes are waiting to run. Usually that's because of lots of things wanting CPU, but not always. A common culprit is a process waiting for IO - disk or network. Try running ps -e v and looking for process state flags. state    The state is given by a sequence of characters, for example, RWNA. The      first character indicates the run state of the process:D    Marks a process in disk (or other short term, uninterruptible) wait.I    Marks a process that is idle (sleeping for longer than about 20 seconds).  L    Marks a process that is waiting to acquire a lock.R    Marks a runnable process.S    Marks a process that is sleeping for less than about 20 seconds.T    Marks a stopped process.W    Marks an idle interrupt thread.Z    Marks a dead process (a zombie).This is from the ps manpage, so you an find more detail there - R and D processes are probably of particular interest. 