Operating Systems 2022F: Tutorial 6 - Revision history

Soma: /* A: Getting Started */

2022-10-31T01:18:48Z

A: Getting Started

← Older revision		Revision as of 01:18, 31 October 2022
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	# Run both programs with the same arguments of your choice. Do this a few times. Do they behave the same way? Do you notice any differences?		# Run both programs with the same arguments of your choice. Do this a few times. Do they behave the same way? Do you notice any differences?
	# Repeat the above experiment, this time running each program under strace (with the -f flag to trace children too). Do you notice any difference in the system calls each program makes?		# Repeat the above experiment, this time running each program under strace (with the -f flag to trace children too). Do you notice any difference in the system calls each program makes?
	# In the next question, you will be playing around with <tt>trace</tt> from bcc-tools. As it makes use of eBPF, a Linux kernel extension mechanism, it needs to be run '''with root privileges'''. (sudo ~~should work on the class VM~~) We will explore eBPF more in later tutorials.		# In the next question, you will be playing around with <tt>trace</tt> from bcc-tools. As it makes use of eBPF, a Linux kernel extension mechanism, it needs to be run '''with root privileges'''. Because the command isn't in a standard directory in the class VMs, you'll need to become root with <tt>sudo -i</tt> and then run trace (rather than sudo trace). We will explore eBPF more in later tutorials.
	# Here are some example <tt>trace</tt> commands to play with. You can learn more about <tt>trace</tt> from its man page. Note these assume you unpacked the 3000pc.zip in the Documents folder.		# Here are some example <tt>trace</tt> commands to play with. You can learn more about <tt>trace</tt> from its man page. Note these assume you unpacked the 3000pc.zip in the Documents folder.
	Report on the string passed to pick_word() on its return:		Report on the string passed to pick_word() on its return:

Soma: /* A: Getting Started */

2022-10-21T18:30:27Z

A: Getting Started

← Older revision		Revision as of 18:30, 21 October 2022
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	trace -p `pidof 3000pc-fifo \| awk '{print $2}'` ...		trace -p `pidof 3000pc-fifo \| awk '{print $2}'` ...

	<tt>trace</tt> allows you to do many things that you can do with gdb; however, it is designed to work on production applications and thus is very efficient and much less intrusive. In technical terms, gdb ~~uses~~ the ptrace system call, while <tt>trace</tt> uses eBPF ~~(a much newer technology)~~.		<tt>trace</tt> allows you to do many things that you can do with gdb; however, it is designed to work on production applications and thus is very efficient and much less intrusive. In technical terms, gdb, strace, and ltrace use the ptrace system call, while <tt>trace</tt> uses eBPF.

	==B: Producer/Consumer with Pipes==		==B: Producer/Consumer with Pipes==

Soma: /* A: Getting Started */

2022-10-21T18:29:23Z

A: Getting Started

← Older revision		Revision as of 18:29, 21 October 2022
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	# Repeat the above experiment, this time running each program under strace (with the -f flag to trace children too). Do you notice any difference in the system calls each program makes?		# Repeat the above experiment, this time running each program under strace (with the -f flag to trace children too). Do you notice any difference in the system calls each program makes?
	# In the next question, you will be playing around with <tt>trace</tt> from bcc-tools. As it makes use of eBPF, a Linux kernel extension mechanism, it needs to be run '''with root privileges'''. (sudo should work on the class VM) We will explore eBPF more in later tutorials.		# In the next question, you will be playing around with <tt>trace</tt> from bcc-tools. As it makes use of eBPF, a Linux kernel extension mechanism, it needs to be run '''with root privileges'''. (sudo should work on the class VM) We will explore eBPF more in later tutorials.
	# Here are some example <tt>trace</tt> commands to play with. You can learn more about <tt>trace</tt> from its man page. Note these assume you unpacked the 3000pc.zip in the Documents folder.		# Here are some example <tt>trace</tt> commands to play with. You can learn more about <tt>trace</tt> from its man page. Note these assume you unpacked the 3000pc.zip in the Documents folder.

	Report on the string passed to pick_word() on its return:		Report on the string passed to pick_word() on its return:

Line 37:		Line 36:

	trace -p `pidof 3000pc-fifo \| awk '{print $2}'` ...		trace -p `pidof 3000pc-fifo \| awk '{print $2}'` ...

			<tt>trace</tt> allows you to do many things that you can do with gdb; however, it is designed to work on production applications and thus is very efficient and much less intrusive. In technical terms, gdb uses the ptrace system call, while <tt>trace</tt> uses eBPF (a much newer technology).

	==B: Producer/Consumer with Pipes==		==B: Producer/Consumer with Pipes==

Soma at 18:26, 21 October 2022

2022-10-21T18:26:25Z

← Older revision		Revision as of 18:26, 21 October 2022
Line 11:		Line 11:
	# Run both programs with the same arguments of your choice. Do this a few times. Do they behave the same way? Do you notice any differences?		# Run both programs with the same arguments of your choice. Do this a few times. Do they behave the same way? Do you notice any differences?
	# Repeat the above experiment, this time running each program under strace (with the -f flag to trace children too). Do you notice any difference in the system calls each program makes?		# Repeat the above experiment, this time running each program under strace (with the -f flag to trace children too). Do you notice any difference in the system calls each program makes?
	# In the next question, you will be playing around with <tt>trace</tt> from bcc-tools. ~~<tt>trace</tt> is very similar to <tt>bpftrace</tt>.~~ As ~~any tool based on~~ eBPF, it needs to be run '''with root privileges'''. (sudo should work on the class VM)		# In the next question, you will be playing around with <tt>trace</tt> from bcc-tools. As it makes use of eBPF, a Linux kernel extension mechanism, it needs to be run '''with root privileges'''. (sudo should work on the class VM) We will explore eBPF more in later tutorials.
	# Here are some example <tt>trace</tt> commands to play with. You can learn more about <tt>trace</tt> from its man page. Note these assume you unpacked the 3000pc.zip in the Documents folder.		# Here are some example <tt>trace</tt> commands to play with. You can learn more about <tt>trace</tt> from its man page. Note these assume you unpacked the 3000pc.zip in the Documents folder.

Soma: Created page with "In this tutorial you'll be learning about two implementations of the [https://en.wikipedia.org/wiki/Producer%E2%80%93consumer_problem producer-consumer problem], a classic example of a concurrency problem. The [http://pages.cs.wisc.edu/~remzi/OSTEP/ class textbook] covers concurrency in great detail in Chapters 25-34, and the producer-consumer problem is covered in [http://pages.cs.wisc.edu/~remzi/OSTEP/threads-cv.pdf Chapter 30 (Condition Variables)] and [http://pages...."

2022-10-21T18:24:08Z

Created page with "In this tutorial you'll be learning about two implementations of the [https://en.wikipedia.org/wiki/Producer%E2%80%93consumer_problem producer-consumer problem], a classic example of a concurrency problem. The [http://pages.cs.wisc.edu/~remzi/OSTEP/ class textbook] covers concurrency in great detail in Chapters 25-34, and the producer-consumer problem is covered in [http://pages.cs.wisc.edu/~remzi/OSTEP/threads-cv.pdf Chapter 30 (Condition Variables)] and [http://pages...."

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