Blog posts
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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.…
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Crashing and burning during lunch & Daily Review – Day ending in 2020/09/16
I had mentioned yesterday that I slept horribly, waking up early and starting day off at around 03:45 AM. That wake up time was brutal and as a result, I crashed and burned in the afternoon, leveraging those precious 30 minutes of my lunch to nap in my wife’s / daughter’s bedroom (a room with…
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Synchronization notes (part 2/2) – Linked Based Queuing lock
In part 1 of synchronization, I talked about the more naive spin locks and other naive approaches that offer only marginally better performance by adding delays or reading cached caches (i.e. avoiding bus traffic) and so on. Of all the locks discussed thus far, the array based queuing lock offers low latency, low contention and…
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Tired like a zombie & Daily Review – Day ending in 2020/09/15
Today is going to be rough. I slept horribly, waking up multiple times throughout the night. Ultimately, I rolled out of my tri-folding foam mattress (a temporary bed while my daughter and wife sleep on the mattress in a separate room as to not wake me up: that parent life) at 03:45 AM this morning.…
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Synchronization (Notes) – Part 1
I broke down the synchronization topic into two parts and this will cover material up to and including the array based queuing lock. I’ll follow up with part 2 tomorrow, which will include the linked list based queuing lock. There a couple different types of synchronization primitives: mutual exclusion and barrier synchronization. Mutual exclusion ensures…
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Honoring my body’s internal alarm clock & Daily Review – Day ending in 2020/09/14
This morning my body woke me up later than usual. After a few blinks, I squeezed the corner of my Casio G-Shock watch, the green background lighting up and shining the time: 05:55 AM. Ugh. About an hour later than I wanted to wake up. On one hand, I’m bummed because I won’t be able…
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Shared Memory Machine Model (notes)
You need to take away the following two themes for shared memory machine model: Difference and relationship between cache coherence (dealt with in hardware) and cache consistency (handled by the operating system) The different memory machine models (e.g. dance hall, symmetric multiprocessing, and distributed shared memory architecture) Cache coherence is the promise delivered by the…
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Losing 2 hours searching for a website bookmark & Weekly Review: week ending in 2020/09/06
My weekly review that normally takes place first thing in the morning on Sundays was completely derailed this time around, all because I could find the URL to a website that I had sworn I bookmarked for my wife’s birthday present. I ended up coughing up two hours of searching: searching directly on Reddit’s website…