Modifiying-CFS-Scheduler

Sneha Sinha - 2016098 & Ritu Kumari - 2016078

Part 1: Compiling the source code

The linux 3.19.0 source code is downloaded and it's extracted.

• cd to that directory
• do 'cp /boot/config-$(uname -r) .config' to copy the kernel's .config file then followed by 'make menuconfig'
• use 'sudo make -j 4 && sudo make modules_install -j 4 && sudo make install -j 4'.The kernel and modules are compiled.
• do 'update-initramfs -c -k 3.19.0' to update the kernel, and 'update-grub' to add it to the grub.

Part 2: Modifying CFS

• Updated /include/linux/sched.h task struct to include srt flags and requirements.
• Updated /kernel/sched/fair.c to include the required scheduling policy for SRT tasks.

Part 3: Making 'rtnice' System Call

• Made info directory in the kernel.
• 'info' directory includes:

1. rtnice.c - C code for System call implementation.
2. rtnice.h - header file.
3. Makefile - Makefile for c code.

• Updated arch/x86/syscalls/syscall64.tbl to include the 'rtnice' system call.
• Updated Linux kernel main Makefile to include the 'rtnice' system call.

Part 4: Testing

• rtnicetest.c tests the rtnice system call and the modified cfs scheduler.

ERRORS:

1. if no task with given PID exists.
2. if timeslice < 1 or greater than a certain value.

PS: Patch can be applied to the linux-kernel 3.19 on Ubuntu Server 14.04.4. (Kernel may go into panic mode. Apply patch on your own risk)