XV6 Operating System

xv6 is a re-implementation of Dennis Ritchie's and Ken Thompson's Unix Version 6 (v6). xv6 loosely follows the structure and style of v6, but is implemented for a modern RISC-V multiprocessor using ANSI C. I added a lottery ticket scheduler, in addition to the default "round-robin" schduler found on xv6. This lottery ticket scheduler assigns every process a number of tickets, and then draws a ticket, and the process that owns the winning ticket is the next process to run.

Building and Running XV6

You will need a RISC-V "newlib" tool chain from https://github.com/riscv/riscv-gnu-toolchain, and qemu compiled for riscv64-softmmu. Once they are installed, and in your shell search path, you can run "make qemu".

Testing the New Lottery Scheduler

For the default round-robin scheduler:

$ make qemu 

For lottery scheduler and equal ticket number assignment:

$ make qemu SCHEDPOLICY=RANDOM

For lottery scheduler and random ticket number assignment:

$ make qemu SCHEDPOLICY=RANDOM RANDOMTICKETNUMBER=RANDOMTICKETTRUE