error: "Invalid argument" setting key "kernel.sched_rt_runtime_us"

Issue

default value for sched_rt_runtime_us kernel parameter is

kernel.sched_rt_runtime_us = 950000

when i am changing the value to 700000 i am getting following message ( while lowering value from default )

# sysctl -w kernel.sched_rt_runtime_us=700000
error: "Invalid argument" setting key "kernel.sched_rt_runtime_us"

when i am increasing the value it is working fine

# sysctl -w kernel.sched_rt_runtime_us=980000
kernel.sched_rt_runtime_us = 980000

How do we change the value of above parameter value (lower the value)?