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T he Linux Kernel A newbie’s guide to the Kernel. Balaji V ijalabv@yahoo.com. Evolution of Operating Systems. Before Multiprogramming “Jobs”, “Offline” Multiprogramming Spooling Timesharing CTSS MULTICS. Minix. Unix becomes proprietary Tanenbaum writes from scratch
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The Linux KernelA newbie’s guide to the Kernel Balaji V ijalabv@yahoo.com
Evolution of Operating Systems • Before Multiprogramming • “Jobs”, “Offline” • Multiprogramming • Spooling • Timesharing • CTSS • MULTICS
Minix • Unix becomes proprietary • Tanenbaum writes from scratch • Unix-like from outside • Readable & teachable • USENET group gets popular • New suggestions, ideas and code offered • Finally, Linux is born
Naming Conventions • Words separated by ‘_’ • Wait_queue • Pointer “ptr”, p_ • p_cptr
Process • What is a process ? • Multiprocessing Operating System • task vector • task_struct • State – Running, waiting, Zombie, stopped • Scheduling Information • Pid
Process (contd) • Links – • Identifiers – uid, gid, effective, FS, saved • Timers – time since start, alarm • Filesystem – VFS inode pointer • Virtual Memory • Processor Specific contexts
Scheduling • Policy – Round Robin, FIFO • Priority • rt_priority • Current Process • Process Selection • Swapping • #ifdef _SMP_
Inter Process Communication • Why ? • Signals • Kill –l • SIGSTOP, SIGKILL • Core dump ! • Why only 32 signals ?