getCPUTime does not work in general

With

fromPicoSeconds picoseconds =
  let (n,k) = divMod picoseconds (10^12) 
  in  normalizeTimeDiff (diffClockTimes (TOD n k) (TOD 0 0))

Then evaluate the following:

replicateM 1000 $ liftM fromPicoSeconds getCPUTime

They all return the same number of picoseconds. Computers aren't that fast. I expected to see at least some different numbers.

Trac metadata

Trac field	Value
Version	6.7
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	GHCi
Test case
Differential revisions
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Operating system	Unknown
Architecture	Unknown