Author: Matt Chung
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Project 2 (barrier synchronization) – Snapshot of my knowledge
The purpose of this post is to take a snapshot of my understanding before I begin working on project 2: implementing (two) synchronization barriers. Although I picked up some theoretical knowledge from both this course (i.e. advanced operating systems) and GIOS (i.e. graduate introduction to operating systems) on barrier synchronization, I actually never implemented barriers…
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Daily Review – Day ending in 2020/09/27
Writing Published a post on the anki settings I used to cram for the midterm exam Family and Friends Walked the dogs at Magnuson Park. Elliott and Jess joined too since Elliott has been waking up so early these days (around 05:45 AM). Trying to get the dogs to capitalize on these amazing off…
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Weekly Review: week ending in 2020/09/27
This past week, I skipped writing my daily reviews for two days in a row because I was really pressed for time. On the days that I skipped, I immediately started studying for the midterm exam as soon as I woke up. Looking back, I regret not writing anything down. Because I’ve already forgotten the…
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My Anki settings for cramming for an exam
I spent a few minutes fiddling with my Anki settings yesterday, modifying the options for the advanced operating systems deck that I had created to help me prepare for the midterm. Although Anki’s default settings are great for committing knowledge and facts over a long period of time (thanks to its internal algorithm exploiting the…
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Shared memory multiprocessing (notes for advanced operating systems)
OS for parallel machines Summary There are many challenges that the OS faces when building for parallel machines: size bloat (features OS just has to run), memory latency (1000:1 ratio) and numa effects (one process accessing another process’s memory across the network), false sharing (although I’m not entirely sure whether false sharing is a net…
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Midterm preparation (part 3/3) – Virtualization to Test-And-Set
Question 3d The algorithm is implemented on a cache coherent architecture with an invalidation-based shared-memory bus. The circular queue is implemented as an array of consecutive bytes in memory such that each waiting thread has a distinct memory location to spin on. Let’s assume there are N threads (each running on distinct processors) waiting…
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Daily Review – Day ending in 2020/09/24
Today I’m posting a super short daily review given that the midterm (for advanced operating systems) opens up in about 13 hours. Writing Published on drifting apart (as part of my daily review) Published my first set of guesses to the mid term questions Parenting and family matters Held Elliott in my arms while we…
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Midterm preparation (part 2/3) – Virtualization to Test-And-Set
This is a continuation of me attempting to answer the midterm questions without peeking at the answers. Part 1 covered questions from OS Structures and this post (part 2) covers virtualization and includes questions revolving around memory management in hypervisors and how to test-and-set atomic operations work. A few useful links I found while trying…
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On building online learning communities & Daily Review – Day ending in 2020/09/23
Thanks to my wife for encouraging me to pull the trigger and start my online study group (i.e. the “war room”) for my advanced operating systems course. Basically, the idea came about after chatting with a class mate of mine and during our video call, I realized how many of us are basically studying alone…
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Midterm preparation – Questions and my guesses for OS Structures section
As mentioned in my recent post on taking a multi pass approach for midterm preparation, I’m taking a stab at answering the midterm questions myself and below are my unfiltered attempts followed by the correct answer that I pulled from the answer key. OS Structures Question 1a Protection domains allow providing independence, integrity, and isolation…
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On drifting apart & Daily Review – Day ending in 2020/09/22
Before stepping into parenthood, my wife and I would often read about other couples scheduling time for being “intimate” (aka sex), time alone just for the two parents. Without this deliberate effort, parents can fall into the trap of focusing 100% of their time on raising their children and forgetting what its like to be…
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Multi pass approach for studying to advanced operating systems midterm (fall 2020)
According to the omscentral reviews for the advanced operating systems course, the midterm exams are nearly identical to the previous semester’s exams and former students strongly suggest rote memorization as a the primary study method. In my opinion, these types of tests do not really serve as a great litmus test for evaluating a student’s…
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Advanced Operating Systems (AOS) notes
If you are an online masters of computer science student (OMSCS) at Georgia Tech and enrolled in advanced operating systems (AOS) course, you might want to check out the notes I’ve taken for the lectures by clicking on the advanced operating systems category on my blog. For each video lecture, I’ve written down a summary…
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Being present in the moment & Daily Review – Day ending in 2020/09/21
Being fully present as a parent all the time seems like an impossible feat. Although I’d like to think that I’m always present with my daughter, I do find myself sometimes mentally checking out. For example, yesterday, Jess had reminded me during lunch I should be in the here and now instead of scrolling on…
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Parallel Systems – Scheduling (notes)
The key take away for scheduling is that as OS designers you want to follow this mantra: “keep the caches warm“. Following this principle will ensure that the scheduler performs well. There are many different scheduling algorithms including first come first serve (FCFS), fixed processor (focus on fairness), fixed processor (thread runs on the same…
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(Re) learning how to doodle & Daily Review – Day ending in 2020/09/20
I’m (re) learning how to doodle! I’d like to incorporate art and sprinkle sketches into notes that I scribble down while studying for graduate school. Also, I just miss drawing, an activity I used to do a lot as little boy. But somewhere between then and becoming an adult I’ve lost my way, losing touch with…
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Remote Procedure Call (RPC) notes
Remote procedure call (RPC) is a framework offered within operating systems (OS) to develop client/server systems and they promote good software engineering practices and promote logical protection domains . But without careful consideration, RPC calls (unlike simple procedure calls) can be cost prohibitive in terms over overhead incurred when marshaling data from client to server…
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Weekly Review: week ending in 2020/09/06
Another installment of my weekly reviews. I think the practice of carving out around 30 minutes on Sunday to look back at the previous week and look forward for the next week helps me in several ways. First, the posts help me recognize my tiny little victories that I often neglect and they also help…
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Barrier Synchronization (Part 2/2)
Part 1 of barrier synchronization covers my notes on the first couple types of synchronization barriers including the naive centralized barrier and the slightly more advanced tree barrier. This post is a continuation and covers the three other barriers: MCS barrier, tournament barrier , dissemination barrier. Summary In the MCS tree barrier, there are two…
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How to convert .heic images to .jpeg using command line on MacBook
My wife’s apple iPhone X saves images she captured with her camera as .heic format1 , a relatively new file format that compresses high quality images and I needed a way to convert these type of files to .jpeg (which apparently dates back to 1992) so that they can be uploaded to my blog and…
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Finally clean air & Daily Review – Day ending in 2020/09/18
Hooray! Today is the first day in a couple weeks that air quality is considered good, at least according to the EPA. I’m so pleased and so grateful for clean air because my wife and daughter have not left the house since the wild fires started a week ago (or was it two weeks —…
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Barrier Synchronization (Part 1/2)
As mentioned previously, there are different types of synchronization primitives that us operating system designers offer. If as an application designer you nee to ensure only one thread can access a piece of shared memory at a time, use a mutual exclusion synchronization primitive. But what about a different scenario in which you need all…
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On letting go & Daily Review – Day ending in 2020/09/17
With working remote and establishing a (somewhat) daily routine (that has become pretty monotonous), it’s sometimes easy to forget that we’re in the midst of a global pandemic. But that reality is amplified because of the recent wild fires, forcing those of us living in the pacific north west (PNW) — and those living in…
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Making sense of the “sense reversing barrier” (synchronization)
What’s the deal with a sense reversing barrier? Even after watching the lectures on the topic, I was still confused as to how a single flag could toggle between two values (true and false) can communicate whether or not all processes (or threads) are running in the same critical section. This concept completely baffled me.…