如何对IO操作进行速率限制？

sudo nano /etc/default/rcS

IO_SCHEDULER=cfq

sudo iotop -o -b --latency --lines 10 --rate 100K --rps_cpus='0-7'

sudo hdparm -B 1M /dev/sda

import sys
import time
import subprocess

sys.stdout.buffer.write('Buffering data to the output...\n')
start_time = time.time()
buffer_size = 1024 * 1024 * 200
buffer_count = 0
buffer_overflow = 0

while time.time() - start_time < 10:
    if len(input("\nEnter Input data to write: ")) > buffer_size * buffer_count:
        sys.stdout.buffer.write("Buffer Overflow! Buffer size exceeded.\n")
        buffer_size = buffer_count
    elif buffer_overflow > 5:
        sys.stdout.buffer.write("\nBuffer Overflow Occurred! Stopping the program...")
        sys.exit(1)
    buffer_count += 1
    
    subprocess.Popen(['dd', 'if=/dev/zero', 'of=/mydata/output.out', 'bs=' + str(buffer_size)], stdout=subprocess.PIPE).communicate()
    subprocess.Popen(['dd', 'if=/dev/zero', 'of=/mydata/input.out', 'bs=' + str(buffer_size)], stdout=subprocess.PIPE).communicate()