Operating Systems 2019F: Assignment 2 - Revision history

Soma at 20:13, 11 October 2019

2019-10-11T20:13:30Z

← Older revision		Revision as of 20:13, 11 October 2019
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	Note time by default outputs to standard error. So, you can get all of your times by adding a "2> times.txt" to the end of the above.		Note time by default outputs to standard error. So, you can get all of your times by adding a "2> times.txt" to the end of the above.

			==Solutions==

			[https://homeostasis.scs.carleton.ca/~soma/os-2019f/solutions/assign2-sol.txt Assignment 2 solutions]

Soma: /* Hints */

2019-10-11T17:51:05Z

Hints

← Older revision		Revision as of 17:51, 11 October 2019
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	This will create a source file with 530M of text. Note you can also use a for loop to run your benchmarks:		This will create a source file with 530M of text. Note you can also use a for loop to run your benchmarks:

	for i in `seq 1 10`; rm dest; do time ./3000redact-rw line source dest; done		for i in `seq 1 10`; do rm dest; time ./3000redact-rw line source dest; done

	Note time by default outputs to standard error. So, you can get all of your times by adding a "2> times.txt" to the end of the above.		Note time by default outputs to standard error. So, you can get all of your times by adding a "2> times.txt" to the end of the above.

Soma at 23:16, 5 October 2019

2019-10-05T23:16:59Z

← Older revision		Revision as of 23:16, 5 October 2019
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	Please submit the answers to the following questions via CULearn by 4 PM on Friday, October 11, 2019. There are 20 points in 10 questions.		Please submit the answers to the following questions via CULearn by 4 PM on Friday, October 11, 2019. There are 20 points in 10 questions.

	Submit your answers as a gzipped tarball named "<username>-comp3000-assign2.~~tar.gz~~" (where username is your MyCarletonOne username). This tarball should expand to a directory with the same name (without .~~tar.gz~~), and in this directory should be the following files:		Submit your answers as a gzipped tarball named "<username>-comp3000-assign2.tgz" (where username is your MyCarletonOne username). This tarball should expand to a directory with the same name (without .tgz), and in this directory should be the following files:

	<username>-comp3000-assign2-answers.txt		<username>-comp3000-assign2-answers.txt
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	So if your username is "janedoe" you'd do the following:		So if your username is "janedoe" you'd do the following:

	tar czf janedoe-comp3000-assign2.~~tar.gz~~ janedoe-comp3000-assign2		tar czf janedoe-comp3000-assign2.tgz janedoe-comp3000-assign2

			(You can extract the file by running tar xzf <tarball>)

	No other formats will be accepted. Submitting in another format will likely result in your assignment not being graded and you receiving no marks for this assignment. In particular do not submit an MS Word or OpenOffice file as your answers document!		No other formats will be accepted. Submitting in another format will likely result in your assignment not being graded and you receiving no marks for this assignment. In particular do not submit an MS Word or OpenOffice file as your answers document!

Soma at 20:57, 5 October 2019

2019-10-05T20:57:07Z

← Older revision		Revision as of 20:57, 5 October 2019
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	Please submit the answers to the following questions via CULearn by 4 PM on Friday, October 11, 2019. There are 20 points in 10 questions.		Please submit the answers to the following questions via CULearn by 4 PM on Friday, October 11, 2019. There are 20 points in 10 questions.

	Submit your answers as a ~~single text file~~ named "<username>-comp3000-assign2.~~txt~~" (where username is your MyCarletonOne username). ~~The first four lines of this file~~ should ~~be "COMP 3000 Assignment 2", your~~ name~~, student number~~, and the ~~date of submission. You may wish to format your answers in Markdown to improve their appearance.~~		Submit your answers as a gzipped tarball named "<username>-comp3000-assign2.tar.gz" (where username is your MyCarletonOne username). This tarball should expand to a directory with the same name (without .tar.gz), and in this directory should be the following files:

	~~When asked~~ to ~~modify source files~~, ~~you~~ may ~~want~~ to ~~give~~ your ~~code~~ in "~~diff~~ -~~c" format~~.		<username>-comp3000-assign2-answers.txt
			3000test-times.c
			redact-mmap.c
			redact-rw.c
			<any other programs you wrote to answer the assignment>

			The first four lines of the answers file should be "COMP 3000 Assignment 2", your name, student number, and the date of submission. You may wish to format your answers in Markdown to improve their appearance.

			You can create a tarball using command

			tar czf <tarfile> <source dir>

			So if your username is "janedoe" you'd do the following:

			tar czf janedoe-comp3000-assign2.tar.gz janedoe-comp3000-assign2

	No other formats will be accepted. Submitting in another format will likely result in your assignment not being graded and you receiving no marks for this assignment. In particular do not submit an MS Word or OpenOffice file as your answers document!		No other formats will be accepted. Submitting in another format will likely result in your assignment not being graded and you receiving no marks for this assignment. In particular do not submit an MS Word or OpenOffice file as your answers document!
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	# [1] Assume you have a file "animal.c". You type <tt>ln -s animal.c penguin.c</tt> in order to create file "penguin.c". If you rename "animal.c" to "animal-base.c", what happens when you try to edit "penguin.c"? Why?		# [1] Assume you have a file "animal.c". You type <tt>ln -s animal.c penguin.c</tt> in order to create file "penguin.c". If you rename "animal.c" to "animal-base.c", what happens when you try to edit "penguin.c"? Why?
	# [2] What symbols are referenced but not defined/allocated in the object file for 3000shell.c (when compiled with -c)? Where (ultimately) is the code or data referred to by these symbols?		# [2] What symbols are referenced but not defined/allocated in the object file for 3000shell.c (when compiled with -c)? Where (ultimately) is the code or data referred to by these symbols?
	# [2] Modify [https://homeostasis.scs.carleton.ca/~soma/os-2017f/code/tut3/3000test.c 3000test.c] so it reports the three times associated with an inode, atime, mtime, and ctime (in a human-readable time format). What do these times mean and when are they updated on files on your system?		# [2] Modify [https://homeostasis.scs.carleton.ca/~soma/os-2017f/code/tut3/3000test.c 3000test.c] so it reports the three times associated with an inode, atime, mtime, and ctime (in a human-readable time format). Call your new program 3000test-times.c. What do these times mean and when are they updated on files on your system?
	# [2] How is the first argument passed to a function in x86-64 assembly? Give an example of this happening in assembly and the corresponding C code.		# [2] How is the first argument passed to a function in x86-64 assembly? Give an example of this happening in assembly and the corresponding C code.
	# [2] What x86-64 register is changed to allocate local variables? Explain briefly with an example.		# [2] What x86-64 register is changed to allocate local variables? Explain briefly with an example.

Soma at 20:44, 5 October 2019

2019-10-05T20:44:43Z

← Older revision		Revision as of 20:44, 5 October 2019
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	~~'''This assignment is not yet finalized.'''~~

	Please submit the answers to the following questions via CULearn by 4 PM on Friday, October 11, 2019. There are 20 points in 10 questions.		Please submit the answers to the following questions via CULearn by 4 PM on Friday, October 11, 2019. There are 20 points in 10 questions.

Soma: /* Hints */

2019-10-05T19:52:08Z

Hints

← Older revision		Revision as of 19:52, 5 October 2019
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	for i in `seq 1 10`; rm dest; do time ./3000redact-rw line source dest; done		for i in `seq 1 10`; rm dest; do time ./3000redact-rw line source dest; done

			Note time by default outputs to standard error. So, you can get all of your times by adding a "2> times.txt" to the end of the above.

Soma: /* Hints */

2019-10-05T19:50:08Z

Hints

← Older revision		Revision as of 19:50, 5 October 2019
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	rm source; echo "This is a line of text" > source; for i in `seq 1 18`; do cat source >> t; cat t >> source; done; rm t		rm source; echo "This is a line of text" > source; for i in `seq 1 18`; do cat source >> t; cat t >> source; done; rm t

	This will create a source file with 530M of text.		This will create a source file with 530M of text. Note you can also use a for loop to run your benchmarks:

			for i in `seq 1 10`; rm dest; do time ./3000redact-rw line source dest; done

Soma: /* Hints */

2019-10-05T19:41:56Z

Hints

← Older revision		Revision as of 19:41, 5 October 2019
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	If you want to create big file for redaction, try something like this:		If you want to create big file for redaction, try something like this:

	rm source; echo "This is a line of text" > source; for i in `seq 1 19`; do cat source >> t; cat t >> source; done; rm t		rm source; echo "This is a line of text" > source; for i in `seq 1 18`; do cat source >> t; cat t >> source; done; rm t

	This will create a source file with ~~about 1.4G~~ of text.		This will create a source file with 530M of text.

Soma: /* Hints */

2019-10-05T19:40:13Z

Hints

← Older revision		Revision as of 19:40, 5 October 2019
Line 28:		Line 28:
	If you want to create big file for redaction, try something like this:		If you want to create big file for redaction, try something like this:

	echo "This is a line of text" > source		rm source; echo "This is a line of text" > source; for i in `seq 1 19`; do cat source >> t; cat t >> source; done; rm t
	for i in `seq 1 20`; do cat source >> t; cat t >> source; done
	rm -f t		This will create a source file with about 1.4G of text.

Soma: /* Questions */

2019-10-05T19:31:22Z

Questions

← Older revision		Revision as of 19:31, 5 October 2019
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	# [3] Compare the performance of <tt>redact-mmap</tt> versus <tt>redact-rw</tt>. Which is faster on large files? Why do you think this is the case? Try using the time command to benchmark your programs, making sure to do at least ten trials.		# [3] Compare the performance of <tt>redact-mmap</tt> versus <tt>redact-rw</tt>. Which is faster on large files? Why do you think this is the case? Try using the time command to benchmark your programs, making sure to do at least ten trials.
	# [3] What happens when process A mmap's file f and process B appends to file f. Will process A see the additional data added to the file by B (if A does no other system calls)? Design an experiment and document your results.		# [3] What happens when process A mmap's file f and process B appends to file f. Will process A see the additional data added to the file by B (if A does no other system calls)? Design an experiment and document your results.

			==Hints==

			If you want to create big file for redaction, try something like this:

			echo "This is a line of text" > source
			for i in `seq 1 20`; do cat source >> t; cat t >> source; done
			rm -f t