cmd/coordinator: make durations more human-friendly

Previously we printed duration to seven decimal points after the
second, which isn't helpful or necessary to determine how long a
build took. Instead, round the duration to the nearest tenth of a
second (if the build took more than 10 seconds), the nearest hundredth
of a second (if it took 1-10 seconds), or the nearest tenth of a
millisecond (if it took less than a second), which should be more than
enough precision and is much easier to read.

Change-Id: I1c29d4a81335bf9ee3cddda0a341d3f321e82f6b
Reviewed-by: Brad Fitzpatrick <>
5 files changed