The duration of worker is wrong

I have a question about the duration of worker.

The CPU time is 2,994.5ms on Nov 22 at 3:35 PM.
The memory limit is 128MB, so I think the duration is 128MB / 1000 * 3sec = 0.384GB-sec.

However, The duration was 2.99GB-sec like the attached image. Why is this?