Transcript Answer 3a

Grade Graph (Assignment 1, 2, 3, & 4 + MT1, 2)
Assuming similar performance in final exam and A5
35
30
number of
students
Actual Distribution
25
Expectation from Survey I
20
15
10
5
0
100+
A
93-100 90-93
A
A-
87-90
B+
83-87
B
80-83
B-
75-80
C+
70-75
C
65-70
C-
0-65
Misc
Score Ranges
Performance is better than expectation in (A, A-) range
CSCI 4061
Introduction to Operating System
Final Review
Rule
• Five/Four students form a group.
• After the questions show up, the team
raises the # card first to get called on
and MUST start to answer the question
when TA calls on them with in 10 seconds
(otherwise lost points)
• Each team gets one AND ONLY ONE
answer per question (within reasonable
time bound).
Difference from normal Jeopardy! game
• Questions are given, you provide the answer.
(not vise versa)
• At most two questions in a row for a group.
After that, all groups are allowed to compete
for the next question.
• When you hear the bell you start to compete
• Only The Jeopardy Round and Final Jeopardy
round
– In final jeopardy round, you can bet up to
all you have
Other logistics
• Gayn is charge of book keeping on white
board (one score per group)
• Priyesh is charge of identify the group that
raise the card first and decided time-out
• Lecturer make FINAL decision whether an
answer is correct or not, we can resolve
disagreement later. No hard feeling ;)
• Some questions would be related to the final
Trophies at stake
– The winning team wins 5 4$ starbuck card.
You can enjoy together after class.
Click to begin.
Click here for
Final Jeopardy
Level
Category A Category B Category C Category D Category E
Processes
Misc.
Concurrency
Comm.
IO
Easy
100 $
100 $
100 $
100 $
100 $
Medium
200 $
200 $
200 $
200 $
200 $
Hard
300 $
300 $
300 $
300 $
300 $
Daunting
400 $
400 $
400 $
400 $
400 $
Impossible
500 $
500 $
500 $
500 $
500 $
Question 1a
When a process will experience an
involuntary context switch.
Answer 1a
Quantum (allocated time) expired
Question 2a
Determine the screen output for
following commands:
variable="Dennis"
echo '$variable'
Answer 2a
$variable
Question 3a
How c-shell evaluates #?var ?
Answer 3a
$?VAR gives “1” if VAR is set, “0” if not.
Question 4a
Which signal is generated when a
privileged instruction is executed in
user mode?
Answer 4a
SIGILL
Question 5a
In CSH/BASH, if you run following
four commands:
cd /mydirectory
ls –l | wc -l
find . –name *.txt > a.txt
Echo success!
How many processes the shell creates.
Answer 5a
3 processes
Question 1b
The name of the block that contains overarching
information about a file system such as size status. Total
number of inodes, free blocks counter and so on.
Answer 1b
Superblock
Question 2b
tianhe@dio (/home/fac26/tianhe) % ls -l
prw------- 1 tianhe mess 0 Dec 8 17:07 trace
What the first character P stands for?
Answer 2b
Named PIPE
first-in, first-out (FIFO) special file.
Question 3b
The name of the situation, in which
constant data swapping between RAM
and disk occurs, when memory is
insufficient for current running
processes.
Answer 3b
Thrashing
Question 4b
With in a directory, you create 5
symbolic links and 7 hard-links. How
many free free-inode are used after
these operations?
Answer 4b
5
Because hard-link only add a (name,
pointer-to-iNode) pair within the
directory file.
Question 5b
Consider a file c (size of 10 bytes) in the
Unix file system named /a/b/c. What is
the minimum number of reads of data
blocks are required to get file c?
Answer 5b
4
Note directory is a file
Data block of /
Data block of a/
Data block of b/
Data block of c
Question 1c
A OS term describes the condition in
which a process is indefinitely delayed,
because other processes are always
given preference.
Answer 1c
starvation
Question 2c
Name at least two necessary conditions
for deadlock
Answer 2c
Hold and wait, circular wait, nonpreempt, mutual exclusion
Question 3c
What is the name of the lock
where the thread simply waits in a loop
repeatedly checking until the lock
becomes available.
Answer 3c
Spinlock
Question 4c
Answer 4c
Question 5c
int i;
for (i = 0; i < 100; i++) {
execlp("echo", "echo", “Hello World\n", NULL);
}
How many lines of text will be print out
Answer 5c
1
Question 1d
List three main elements in protocol
design.
Answer 1d
Format, Order, and Action (FOA)
Question 2d
The server that listens to port Number
21
Answer 2d
FTP
Question 3d
How many sockets are created when
11 users query a DNS server at both
client and server sides
Answer 3d
1 at the UDP server side, 11 at the
client side, totally 12.
Question 4d
The name of a UNIX shell command
used to query Internet domain name
servers
Answer 4d
nslookup
Question 5d
The name of ports 49,152 through 65,535
Answer 5d
Ephemeral ports
Port 0 is reserved
Ports 1 - 1023 are named "well-known" ports
Ports 1024 - 49,151 are registered ports.
Ports 49,152 - 65,535 are ephemeral ports
Question 1e
DOS was the first widely-installed
operating system for personal
computers. What does DOS stand for?
Answer 1e
Disk Operating System
Question 2e
The name of problem a 32 bit time_t data structure
would cause?
Hint( it records the seconds elapsed since January
1, 1970 )
Answer 2e
Year 2038 Problem
It overflows after 03:14:07 UTC on Tuesday,
January 19, 2038.
Question 3e
The name of a small privileged OS core that
provides process scheduling, memory
management, and communication services
and relies on other processes to perform
some of the functions traditionally
associated with the operating system kernel.
Answer 3e
microkernel
Question 4e
Answer 4e
Question 5e
Name at least 4 UNIX-Like OS.
Answer 5e
GNU, FreeBSD, NetBSD, OpenBSD,
SunOS/Solaris MacOS, Linux, HPUX, AIX, UnixWare, IRIX
Question 1f
Answer 1f
Question 2f
Answer 2f
Question 3f
Answer 3f
Question 4f
Answer 4f
Question 5f
Answer 5f
Make your wager up to what you have
Write down the wager along with the
answer on the back of the index card.
Final Question
Consider the following piece of code.
int main(int argc, char ** argv){
int i;
for (i = 0; i < 3; i++) {
fork();
printf("#%d, ", i);
}
printf("\n");
}
What is printed to standard output? Why?
Final Answer
#0, #1, #2,
#0, #1, #2,
#0, #1, #2,
#0, #1, #2,
#0, #1, #2,
#0, #1, #2,
#0, #1, #2,
#0, #1, #2,
This is because printf has an internal user level
buffer that gets copied, when the fork happens,
and since stdout isn’t flushed until
it sees a newline (or fills up the internal buffer), all
8 processes wind up with 0, 1, and 2 in their
buffer. When they exit, the buffers are flushed.
Formal Class Evaluation
Lecture: Tian He
TA: Gyan Ranjan
TA: Priyesh Jain
Your positive feedback is very
important to me and TAs!
Thank you for taking this course.