cmp(1) has a bottleneck, but where?

[Dieter BSD]

>>>> Task: cp(1) a several-GB file from one drive to another,
>>>> then run cmp(1) to verify. Cp runs as expected, but
>>>> cmp runs slower than expected. Neither the disks
>>>> nor the cpu is maxed out. Local drives, no network
>>>> involved. Machine is otherwise idle.
>>>
>>> 1. How are you running cmp?
>>> 2. Why do you claim cmp is the bottleneck? Is it spinning the CPU?
>>
>> cmp big_file /other_disk/big_file
>>
>> Cmp is running slower than it should. It isn't cpu bound ( 67.5%Idle )
>> but it isn't disk bound either. Seems like it should be one or the
>> other.
>
>    What gets output on the console when you do CTRL-T?

load: 0.59  cmd: cmp 93304 [vnread] 56.99r 8.50u 3.80s 23% 720k
load: 0.59  cmd: cmp 93304 [vnread] 57.68r 8.60u 3.85s 22% 720k
load: 0.54  cmd: cmp 93304 [vnread] 60.69r 9.03u 4.12s 22% 780k
load: 0.54  cmd: cmp 93304 [runnable] 63.79r 9.58u 4.26s 22% 720k
load: 0.58  cmd: cmp 93304 [runnable] 68.33r 10.28u 4.62s 21% 788k
load: 0.53  cmd: cmp 93304 [runnable] 71.92r 10.78u 4.94s 23% 720k
load: 0.53  cmd: cmp 93304 [vnread] 72.31r 10.84u 4.96s 21% 780k
load: 0.44  cmd: cmp 93304 [vnread] 198.84r 30.64u 14.36s 23% 720k