Blog posts
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Remembering September 11 & Daily Review (day ending on 09/11/2020)
Yesterday was September 11. On this day, every year, Americans grieve and we are all reminded of the unforgettable day back in 2001 when the New York twin towers collapsed to the ground after being struck by the hijacked planes. I sure remember the day. I was about 12 years old at the time and…
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CPU and Device Virtualization (notes)
This post is a continuation of virtualization. In the previous post, I talked about memory virtualization. This post instead discusses CPU and device virtualization. Ultimately, as system designers, one of our chief aims is to provide an illusion to the underlying guest operating systems that they each individually won the underlying hardware, the CPU and…
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Memory coordinator test cases (and expected outcome)
I’m getting ready to begin developing a memory coordinator for project 1 but before I write a single line of (C) code, I want to run the provided test cases and read the output of the tests so that a get a better grip of the memory coordinator’s actual objective. I’ll refer back to these…
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Daily Review – Day ending in 2020/09/10
We often talk about work life balance, separating the two major parts of our lives. On some level, I agree with the philosophy, believe that work is work and life is life. But at least for me, what happens at work bleeds into my personal life, and vice versa. When I have a shitty day…
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Memory Virtualization (notes)
The operating system maintains a per process data structure called a page table, creating a protection domain and hardware address space: another virtualization technique. This page table maps the virtual address space to physical frame number (PFN). The same virtualization technique is adopted by hypervisors (e.g. VMWare). They too have the responsibility of mapping the…
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Daily Review – Day ending in 2020/09/09
After freeing a spider into the front yard, I noticed that the coffee mug (in which I trapped the spider in) was decorated with a beautiful web that the spider must’ve spun overnight. Almost every other day, I spot a spider dancing across the white walls of my bedroom. Instead of squishing them to death…
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Papers to read for designing and writing up the C memory coordinator
Below are some memory management research papers that my classmate shared with the rest of us on Piazza1. Quickly scanning over the papers, I think the material will point me in the right direction and will paint a clearer picture of how I might want to approach writing my memory coordinator. I do wonder if…
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How to obtain the length of the memory statistics array when calling virDomainMemoryStats
Up to ‘nr_stats’ elements of ‘stats’ will be populated with memory statistics from the domain. Only statistics supported by the domain, the driver, and this version of libvirt will be returned. What does the above API description even mean by nr_stats? How do you determine the number of elements that need to be populated? For…
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Daily Review – Day ending in 2020/09/08
The most interesting side effect of writing these daily reviews is that they stir up meaningful conversations with my wife. Apparently, much of what words I set on paper never make their way out of my mouth (despite thinking that I did verbally share them). Surely this situation of my brain tricking me into thinking…
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A snapshot of my understanding before tackling the memory coordinator
Now that I finished writing the vCPU scheduler for project 1, I’m moving on to the second part of the project called the “memory coordinator” and here I’m posting a similar blog post to a snapshot of my understanding of project 1 , the motivation being that I take for granted what I learned throughout…
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Quotes from “My life story” by Veritasium
During some down time this evening, I watched the below YouTube video clip filmed and produced by Veritasium and I absolutely loved hearing about his journey, especially about how becoming a father has fundamentally changed the way he views his time. Because I’m in a similar boat: My life looks nothing like it did a…
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Introduction to virtualization (notes)
As system designers, our goal is to design a “black box” system that create an illusion that our users have full and independent access to the underlying hardware of the system. This is merely an abstraction since we are building multi-tenant systems with many applications and many virtual guest machines running on a single piece…
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Daily Review – Day ending in 2020/09/07
Yesterday Writing Blogged and published an entry describing my naive scheduler for project 1 Emotions I disassociated and my mind wandered into its “own world” after my wife Jess asked me to watch Elliott later that afternoon. I think part of the reason why I got so worked up had less to do with her…
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A naive round robin CPU scheduler
A couple days ago, I spent maybe an hour whipping together a vary naive CPU scheduler for project 1 in advanced operating systems. This naive scheduler pins each of the virtual CPUs in a round robin fashion, not taking utilization (or any other factor) into consideration. For example, say we have four virtual CPUs and…
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Distancing oneself from a difficult problem
I fixed a silly bug just now and wrote working code that can pin multiple virtual CPUs to the physical CPUs. Identifying the bug in my code was another classic example of how I needed to distance myself from the problem. Instead of staying up late into the night (late is now 09:30 pm on…
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Weekly Review – Week ending in 2020/09/06
Writing I’m getting much more comfortable with publishing blog posts that are not completely polished. The fear of letting the world see less my less the perfect propose is utter non-sense. In fact, writing and publishing frequently offers two benefits. The first is that the sheer act of writing and setting words on (digital) paper…
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Advanced Operating Systems (Project 1) – monitoring CPU affinity before launching my own scheduler
Project 1 requires that we write a CPU scheduler and memory coordinator. Right now, I’m focusing my attention on the former and the objective for this part of the project is write some C code that pins virtual CPUs to physical CPUs based off of the utilization statistics gathered with the libvrt library (I was…
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Daily Review – Day ending in 2020/09/04
Yesterday Writing Blogged and published an entry for my daily review Blogged and published an entry explaining the libvrt’s bit map data structures that map virtual CPUs to physical CPUs Music Noodled around on the guitar, playing chords in a minor key up the neck (need to start structuring and mixing up my practice sessions…
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Making sense of libvrt bit map when calling virDomainPinVcpu
On my iPad this morning, I doodled the above figure to help me better understand how I should be calling the function virDomainPinVcpu (as part of project 1 for my advanced operating systems course). The function requires two parameters which I found a bit confusing: a pointer to the cpu map (i.e. bit map) and…
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Daily Review – Day ending in 2020/09/03
Writing Blogged and published an entry for my daily review Blogged and published an entry on L3 Microkernel Mental and Physical Health At the park, ran around in circles while holding Elliott in my arms … that sort of counts as exercise, right? Music Nothing at all Graduate School Migrated from my Virtualbox environment to…
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L3 Microkernel
I learned that with an L3 Microkernel approach, each OS runs in their own address space and that they are indistinguishable from the end-user applications running in user land. Because they run in user land, it seems intuitive that this kill performance due to border crossings (not just necessarily context switching, but address space switching…
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Daily Review – Day ending in 2020/09/02
Writing Blogged and published an entry for my daily review Blogged and published an entry that shows the steps for building librty’s documentation from source code (since the manual no longer exists on the official website) Mental and Physical Health Met with my therapist, who I see every week (except last week since I had…
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How to build the libvrt documentation from source
If just download the libvert application development guide, click here. How to build the documentation The libvrt developer documentation link is broken (i.e. HTTP 404). But I need the development guide for my advanced OS course so I downloaded the repository and built the documentation from source. If you want to do the same…
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Why do people fall prey to pyramid schemes?
YouTube’s recommendation engine suggested that I watch a video called “The Cult of Dan Lok”. Mind you, I never even heard of Dan Lok but my intuition lead me to believe that he runs some sort of pyramid scheme. Surprise surprise: he does. Anyways, in the video below, a student of Dan Lok describes how…