1 Linux pthreads and their scheduling (Total points:
80).
1.1 Thread scheduling
This exercise is to show you how to use Linux’s scheduling policies for three threads. You need to launch three threads, each of which relies on three different functions, countA(), countB() and countC(). Each function does the same thing, i.e. counts from 1 – 232. The following should be the detailed specification of each of the threads, to being with:
1. Thread 1 (call it Thr-A()): Uses SCHED OTHER scheduling discipline with standard priority (nice:0).
2. Thread 2 (call it Thr-B()): Uses SCHED RR scheduling discipline with default priority.
3. Thread 3 (call it Thr-C()): Uses SCHED FIFO scheduling discipline with default priority.
Each of these threads must time the process of counting from 1 – 232. You can use the clock gettime() function for obtaining the actual time ticks that can be used to compute how long it took to complete a function.
We require you benchmark these three schedulers by change the scheduling priorities of the three threads (keeping the scheduling priorities the same), against the counting program.
For these cases, you would require to rely on pthread schedsetparam() and related functions for the same. You would require to generate histograms showing which scheduler completes the task when, depending upon the scheduling policy. You may choose different colors for the histogram bars, with one axis showing the time to complete, and the other showing the thread priorities. Of course, you cannot plot for all possible values of priorities; you would require to choose only some.
1.2 Process scheduling
This part of the exercise, involves creating three process, instead of the three threads. Each of these process should involve compiling a copy of the Linux kernel source (with the minimal config shared by the TAs earlier). The three processes should be created with fork() and thereafter the child processes should use execl() family system calls to run a different a different bash script, each of which should be having the commands to compile a copy of the kernel. To time the execution, the parent process could get the clock timestamp (using clock gettime()) before the fork and after each process terminates (the event of which could be identified when the blocking system call waitpid()) returns.
