Parallelism

SQL> insert /*+ APPEND */ into LOG select /*+ PARALLEL(8) */ * from LOG6;

What I don't understand is that parallelism is practically non-existing:

op - 14:19:11 up 20 days, 23:54,  5 users,  load average: 1.14, 0.92, 0.77 Tasks: 680 total,   3 running, 474 sleeping,   0 stopped,   0 zombie %Cpu(s):  2.7 us,  0.5 sy,  0.0 ni, 96.3 id,  0.4 wa, 0.0 hi,  0.2 si,  0.0 st
KiB Mem : 65613180 total,  6174376 free, 39190992 used, 20247812 buff/cache KiB Swap: 29241340 total, 29241340 free,        0 used. 23073784 avail Mem

   PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
  7786 oracle    20   0 1408616 405472  61564 R  84.8 0.6   3:08.25 oracle
  6500 oracle    20   0 1086016  61332  54420 S   1.7 0.1   1:11.46 oracle
  6510 oracle    20   0 1086016  65652  58632 S   1.7 0.1   1:10.09 oracle
  6512 oracle    20   0 1070028  53456  47772 R   1.7 0.1   0:12.96 oracle
  6514 oracle    20   0 1070028  53928  48040 S   1.7 0.1   0:12.73 oracle
  6502 oracle    20   0 1086076  61124  54168 S   1.3 0.1   1:12.68 oracle

I thought that there will be 8 processes spending significant amount of CPU resources. The process burning CPU is doing no IO:

[root_at_carpo ~]# strace -e trace=file -p 7786

strace: Process 7786 attached
strace: [ Process PID=7786 runs in x32 mode. ]
strace: [ Process PID=7786 runs in 64 bit mode. ]

That is probably to be expected because processes do not burn CPU while doing IO. What exactly is that process doing?