Cpsc 457 Operating Systems, Winter 2003

Announcements about Cpsc457 will appear on this page

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TENTATIVE RESULTS will be posted on about JAN 02 2004 at the CPSC MAIN OFFICE.

Posted will be TENTATIVE GRADE, TOTAL SCORE, FINAL EXAM MARK, MT MARK, and LAB MARK. The TOTAL SCORE should equal FINAL + MT + LABS. If you spot a clerical error, email me about it.

FINAL GRADES will be submitted to the Registrar on Jan 07 (the deadline).

Merry Christmas and a Happy New Year

Welcome Back!
Dec 03, 2003

Questions on the final examination will concentrate on material from chapters 5, 6,(not 7,) 8, 9, 10, 11, 12, (not 13,) 14, but you are exoected to have a good working knowledge of Chapters 1-4 as well.

Chapter 5: Sections 5.1 5.2, 5.4
Chapter 6: 6.1 - 6.6
Chapter 8: All
Chapter 9: All except 9.1.3, 9.1.4, 9.1.5 and 9.6
Chapter 10: All except 10.7
Chapter 11: As far as end of 11.3.3
Chapter 12: 12.1, 12.4, 12.5
Chapter 14: 14.2, and read 14.5 on RAID

There is a sample Final examination for you to try.

Answers to the Sample Exam are at the bottom of this web page

Welcome Back!
Nov 19, 2003

We have now finished Chapter 9 on memory management as far as Paging and some Segmentation. We now go on to Demand Paging or Virtual Memory in Chapter 10. Please read ahead.

A Database text book (Cpsc471) was found in the Cpsc457 class (ICT114) today. The owner can get it from the Cpsc Main Office.

Welcome Back!
Nov 6, 2003

We have finished with Deadlocks (all of Chapter 8) and are now covering Threads (Chapter 4).

We are only taking an overview look at threads, as this is an evolving area. Be careful to distingush between

(1) User Threads, that is, application program threads supported by a library of supporting routines, such as POSIX Pthreads, and

(2) Kernel Threads, that is, application program threads supported directly by the OS.

In Chapter 4, read Sections 1, 2 and 4. You can read other sections if you are curious, but the smoke hasn't cleared in this area yet.

Later in Friday's class we will be starting on Memory Management, in Chapter 9.

Welcome Back!
Oct 29, 2003

As soon as we finish Chapter 6 (today in class), we proceed to Chapter 8 on Deadlocks, which we cover in detail.

LOST CALCULATOR IN MID TERM EXAM

Some one sitting in Row 2 near the south door left a calculator behind. See Suzan in Main Cpsc Office (ICT Floor 6).

Welcome Back!
Oct 15, 2003

The mid term examination is on Wed., Oct 22, and is OPEN BOOK. You may bring the text book, and notes. A calculator may be useful but is not necessary.

For the mid term, study
Chapters 1-3 as far as the end of Section 3.5
Chapter 4 as far as the end of Section 4.4
Chapter 7 as far as the end of Section 7.6. Binary semaphores are not on.
Chapter 6 as far as the end of the material on SJF
Any handouts.

There is a sample midterm examination for you to try. This sample exam will be covered in class on Monday Oct 20. The results of the mid term should be available in class on Friday Oct 24.

Note on Moving Averages and SJF

There are three basic types of Moving Average.

1. Simple n-point M.A.
This is computed as the average of the most recent n points in the time series. MA_n = (p1 + p2 + ... + pn)/n or, alternatively, MA_n = p1 * 1/n + p2 * /1/n + ... + pn * 1/n, that is, equal weights of 1/n adding up to 1.0.
The simple n-point M.A. has a calculation shortcut. If pn is the most recent point, the next M.A value MA_(n+1) is related to the previous M.A. value MA_n by:
MA_(n+1) = MA_n - p1 * 1/n + p_(n+1) * 1/n
where p_(n+1) is the subsequent point.

2.Simple weighted n-point M.A.
Here we compute the MA as p1 * w1 + p2 *w2 + ... + pn * wn where w1, w2 ...wn are the weights, and w1 + w2 + ... + wn = 1.0. The idea is to put more weight on the most recent points, so that typically wn > ...> w2 > w1. There is no shortcut for the weighted M.A.

3. Exponential(weighted) M.A.
This is a weighted M.A that uses ALL the points in the time series, no matter how many. It is also weighted, typically with more weight on the most recent points. It has a short cut calculation method available. See the text. You need a shortcut, since otherwise the calculations would slow down the scheduler too much.

* * * C O P Y I N G * * *

So far we have detected 4 students apparently involved in copying with Assignment 1. Because we have two parallel offerings of this course, I have discovered that any case of copying is immediately taken out of my hands, and is taken up by the Department according to faculty rules, which are not lenient. We also have have very good TA's, with eyes in the backs of their heads. So, for your own good, do not attempt to copy. Do your own work, for better or for worse. If you copy, you'll be caught. Crime still doesn't pay.

Welcome Back!
Oct 07, 2003

We have now finished with Chapter 7. We have covered as far as the end of Section 7.6 on region statements. Don't forget that there are three region statements:

Simple: region V do S;

Conditional:
region V when (B) do S; or;
region (B) do begin await(B); S; end;

General:
region V {S0; when (B) do S1;}; or:
region V do begin S0; await (B); S1; end;