Get CPU and memory usage of the process and its children

How to

pgrep -P $(pgrep -f the_process_name) | xargs ps -o %mem,%cpu,cmd -p | awk '{memory+=$1;cpu+=$2} END {print memory,cpu}'

examples

pgrep -P $(pgrep -f navigation_process) | xargs ps -o %mem,%cpu,cmd -p | awk '{memory+=$1;cpu+=$2} END {print memory,cpu}'
pgrep -P $(pgrep -f localization_process) | xargs ps -o %mem,%cpu,cmd -p | awk '{memory+=$1;cpu+=$2} END {print memory,cpu}'

outputs

0.4 63.5
1 469

first column : memory usage

second column : cpu usage - 469% --> the percentage based on 1 core

it means that localization_process & its children use as many resources as 4 cores(469%)