$ strace -e nanosleep perl -MTime::HiRes=sleep -le 'sleep 1.e-6'
nanosleep({0, 0}, NULL)                 = 0
Process 12719 detached
$ strace -e nanosleep perl -MTime::HiRes=sleep -le 'sleep 1.01e-6'
nanosleep({0, 1000}, NULL)              = 0
Process 12721 detached