Using Linux at Northern Michigan University Northern Michigan

Using Linux at Northern Michigan University

Northern Michigan University • Regional University • Normal quality students – Some great – Some struggle • About 9, 000 students and 200 majors • Have some money

NMU’s Computers • Every student gets a laptop – We load them with Java, C++, Pu. TTY – We haven’t had success with VNC – We may not load them with Linux • We have a Laboratory – Kinda silly with all the laptops – Great for system admin class

Advantages of Linux • Source code available – But it’s huge – Parts are interesting • System very inspectable – Can see what’s happening inside

System Admin Class • Teach Basic Linux Admin – Incoming students typically juniors – Lots of students from CIS, a few from the town – Assume students don’t know nothin’ • Frustrates some students • Works for others

Goals of System Admin Class – Add/del users – Networking (NFS, Samba, YP, net printing) – Compile the kernel – Become YP/NIS server and client – Taste shell and perl programming – Independent learning – DEBUGGING SKILLS ARE VITAL

Pride of Ownership • Everyone gets their own computer • They install everything on it • When it breaks, it’s their fault.

Fences Make Good Neighbors • Get a firewall between your lab and the world. – Leave access to the departmental server – Deny access to the world – Files are forced to move through the departmental server

Teach How to Debug • • Break their computers for them. Give a lousy error message. Give points for fixing the problems. Everyone gets a unique problem set.

Never Let Students Hack Each Others Computer!!!!!

The Problem List Points: 10 Task: Fix telnetting to euclid ---Points: 15 Task: I cannot ping Euclid ---Points: 5 Task: What is your ethernet hardware (mac) address? ---- Task: Fix telnetting to euclid Cause: add "198. 110. 193. 8 euclid. nmu. edu" to /etc/hosts ---Task: I cannot ping Euclid Cause: Add the line 'exit' to the script /etc/rc. d/init. d/network ---Task: What is your ethernet hardware (mac) address? Cause: Just ask

No Cheating (kinda) • Don’t let students keep backup copies of /etc

Grading is Important • Don’t use a dumb grading scheme. • If you give points for labs… – Then assignments will be 0% or 100% • You must use tests and broken-labs too.

Operating System Class • Students are seniors. • Goals are OS algorithms, not too much code.

Using Kernel Source • Don’t make them compile kernels. • Do show them code. – Size – Grep for “stupid”. • 106 stupids, 32 of the “other” word – Show easy parts • Old scheduler • Read syscall

Kernel Size

Top is Interesting 11: 08 pm up 61 days, 5: 45, 16 users, load average: 0. 00, 0. 00 84 processes: 81 sleeping, 1 running, 2 zombie, 0 stopped CPU 0 states: 0. 1% user, 0. 1% system, 0. 0% nice, 98. 0% idle CPU 1 states: 0. 0% user, 0. 0% system, 0. 0% nice, 100. 0% idle Mem: 512920 K av, 497660 K used, 15260 K free, 356 K shrd, Swap: 497972 K av, 9324 K used, 488648 K free PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME COMMAN 422 randy 15 0 1040 1036 820 R 2. 8 0. 2 0: 00 top 1 root 8 0 116 68 68 S 0. 0 0: 04 init 2 root 9 0 0 SW 0. 0 0: 00 keven

Strace is Interesting • strace /bin/ls – Uses 119 syscalls – Open 21 files!!!!!! – Writes 3 times. – Goal: Give a real picture for how things work

Benchmarking • Easy to make a benchmark • Time consuming to run them • Whole class can do one run • Always experimental error

Benchmarking Ideas • Compile time vs RAM • Read time vs read size – Never get to disk performance • Which is faster, open or read?

Independent Study • • Linux inspires kids. Source code is available Lots of tools Linux is new – There are projects to be done. – Can effect the world!

Linux Benchmarking Project • Three kids • Is the kernel bloated and slow? – Compare new and old kernels – Count lines – Use lmbench • Teacher was interested, too!

Benchmarking Results • Experimental Errors Experienced. – Teamwork errors too! • • Email from Linux, Alan Cox, etc. Article on Slashdot Speech at Argonne National Lab. Professional Recognition

Unexpected Learning • Army comes to arrest fellow prof – They were very nice people. – Student interest in security soars. – Learning happened – ACS is angry

Unexpected Learning (cont) • We shutdown campus. net – And a business in California – Students suddenly interested in our connectivity – Internet law became interesting too.

Conclusion • Good Teaching is good teaching! – Need to be enthused. – Need to be hands-on. – Need to show examples.

Linux Helps with Teaching • Showing code examples. • Inspect a running system