Invokes `taskset` on the child threads of the specified processes.

taskset_child_threads.sh

#!/bin/bash
# Copyright 2013-2019 Neomantra BV. All rights reserved.
# Released under the MIT License.

usage()
{
    cat >&2 <<EOF
usage:  $0 [-h] [-v] [-c cpulist] ppid1 [ppid2 [...]]

    Given a list of parent process IDs, this script finds their child
    threads using the /proc filesystem.  It then tasksets these child threads
    (but not the parent), to the cpulist.
    
    If -c is not specified, then it just prints the thread IDs.

    Must be run as the user that owns those cmds (or root).

EOF
}

unset THE_CPULIST
VERBOSE=

while getopts "hv?c:" opt ; do
    case "$opt" in
        c) THE_CPULIST=$OPTARG ;;
        v) VERBOSE=1 ;;
        h) usage ; exit ;;
        [?]) usage ; exit ;;
    esac
done
shift $((OPTIND-1))


# Needs ppid arguments
if (($# == 0)) ; then
    usage
    exit 1
fi


# Iterate the pids, taskset-ing the child processes
for ppid in "$@" ; do
    TASKPIDS=$(ls -1 /proc/$ppid/task | grep -v $ppid)
    if [[ -z "$THE_CPULIST" ]] ; then
        echo "$TASKPIDS"
    else
        for pid in $TASKPIDS 
        do 
            if [[ -z $VERBOSE ]] ; then
                taskset -pc "$THE_CPULIST" $pid > /dev/null
            else
                taskset -pc "$THE_CPULIST" $pid
            fi
        done
    fi
done