use another thread loading file for other threads parse will not speed up application

Multithreads load and parse file will notspeedup file handling. because load data from harddisk to memory is notthe CPU's business, so the only function the loading thread is bufferthe data for other threads, and the truth is harddisk already has itsown physical buffer used for speed up file loading, so for the big gdsloading case, use a unique thread loads file from harddisk will speedup nothing.

for another case, one thread load and several threads handle the data.

if HD data handling speed < CPU data handing speed, the CPU will alway stay hungry for data, so one thread is enough,

so now we suppose the hardisk handing data speed is 2 and CPU handling data speed is 1.

HD                CPU

SPEED M/s     2                    1

 

threads number    1                    2                    3

     100% *1     100%*2            66%*3

 

This is the ideal stuation, and use 2CPUs aready reach the peak, if so how to speed up our application anddo we need a thread prepare data for other threads? yes, we can preparethe exact data for others help us to reach the ideal stuation, however,the speedup will not be significate and the job will be very verycomplex.