multiprocessing - How to increases the CPU usage of my Python program? -

i writing program in raspberry pi 3 read inputs using mcp3008 adc function generator. want read 2 channels @ same time , write file. when have 1 channel, 12000 samples per second, however, when have 2 channels, 6000 samples per second each channel. 12000 samples per second each channels, tried write 2 different scripts, 1 each channel , run them simultaneously in 2 different terminals. however, not solve problem , gives me 6000 samples per second each channel.

when have 1 script, 9% cpu usage. when run 2 scripts @ same time in 2 different terminals, 5% cpu usage each process. how each process use 9% cpu each or higher?

thank you!

here code:

import spidev, time, os  # opens spi bus spi = spidev.spidev() spi.open(0, 0)  #spi1 = spidev.spidev() #spi1.open(0, 1)  ch0 = 0 #ch1 = 1  = time.time() * 1000 data = open("test_plot.dat", "w") #data1 = open("test_plot_1.dat", "w")  def getreading(channel):     # pull raw data chip     rawdata = spi.xfer([1, (8 + channel) << 4, 0])     # process raw data understand     processeddata = ((rawdata[1]&3) << 8) + rawdata[2]     return processeddata """ def getreading1(channel):     # pull raw data chip     rawdata = spi1.xfer([1, (8 + channel) << 4, 0])     # process raw data understand     processeddata = ((rawdata[1]&3) << 8) + rawdata[2]     return processeddata """ while true:     if (((time.time() * 1000) - now) < 10001):         data.write("%d\n" % getreading(ch0))         #data1.write("%d\n" % getreading1(ch1))     else:         break  # http://www.takaitra.com/posts/492