what-happens-when
compiler-explorer
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76 | 191 | |
38,967 | 15,295 | |
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0.0 | 9.9 | |
1 day ago | 1 day ago | |
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- | BSD 2-clause "Simplified" License |
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what-happens-when
- What-Happens-When: An attempt to answer an age-old interview question
- What Happens When
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We have used too many levels of abstractions and now the future looks bleak
Agreed!
It reminds me of:
https://github.com/alex/what-happens-when
and how many of today’s CS-degree holders would barely understand any of it. As someone who has also “grown up with all the technology”, I’ve learned and experienced all that. But as a percentage of “software engineers”, there’s fewer and fewer that do every day.
- Step-by-step events when Browsing www.facebook.com after computer bootup.
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I just blew my interview!
There is a pretty comprehensive answer to number 2 here
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Are you skeptical about candidates that call themselves a "10x engineer"?
Ask them to describe what happens when you visit a website and grill them on every layer of abstraction, every implementation detail.
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You and me Anon, you and me
This is a classic interview question and it basically means "How does internet work?" It is great because it allows to check how many levels of understanding it a developer has. The answer may be quite lengthy, for example: https://github.com/alex/what-happens-when
- Any course that actually teaches me how a website is built?
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I have a question about subdomains and their DNS resolution
Perhaps you will find https://github.com/alex/what-happens-when useful.
- Tried and true interview questions/tasks
compiler-explorer
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What if null was an Object in Java?
At least on android arm64, looks like a `dmb ishst` is emitted after the constructor, which allows future loads to not need an explicit barrier. Removing `final` from the field causes that barrier to not be emitted.
https://godbolt.org/#g:!((g:!((g:!((h:codeEditor,i:(filename...
- Ask HN: Which books/resources to understand modern Assembler?
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3rd Edition of Programming: Principles and Practice Using C++ by Stroustrup
You said You won't get "extreme performance" from C++ because it is buried under the weight of decades of compatibility hacks.
Now your whole comment is about vector behavior. You haven't talked about what 'decades of compatibility hacks' are holding back performance. Whatever behavior you want from a vector is not a language limitation.
You could write your own vector and be done with it, although I'm still not sure what you mean, since once you reserve capacity a vector still doubles capacity when you overrun it. The reason this is never a performance obstacle is that if you're going to use more memory anyway, you reserve more up front. This is what any normal programmer does and they move on.
Show what you mean here:
https://godbolt.org/
I've never used ISPC. It's somewhat interesting although since it's Intel focused of course it's not actually portable.
I guess now the goal posts are shifting. First it was that "C++ as a language has performance limitations" now it's "rust has a vector that has a function I want and also I want SIMD stuff that doesn't exist. It does exist? not like that!"
Try to stay on track. You said there were "decades of compatibility hacks" holding back C++ performance then you went down a rabbit hole that has nothing to do with supporting that.
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C++ Insights – See your source code with the eyes of a compiler
C++ Insights is available online at https://cppinsights.io/
It is also available at a touch of a button within the most excellent https://godbolt.org/
along side the button that takes your code sample to https://quick-bench.com/
Those sites and https://cppreference.com/ are what I'm using constantly while coding.
I recently discovered https://whitebox.systems/ It's a local app with a $69 one-time charge. And, it only really works with "C With Classes" style functions. But, it looks promising as another productivity boost.
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Ask HN: How can I learn about performance optimization?
[P&H RISC] https://www.google.com/books/edition/_/e8DvDwAAQBAJ
Compiler Explorer by Matt Godbolt [Godbolt] can help better understand what code a compiler generates under different circumstances.
[Godbolt] https://godbolt.org
The official CPU architecture manuals from CPU vendors are surprisingly readable and information-rich. I only read the fragments that I need or that I am interested in and move on. Here is the Intel’s one [Intel]. I use the Combined Volume Set, which is a huge PDF comprising all the ten volumes. It is easier to search in when it’s all in one file. I can open several copies on different pages to make navigation easier.
Intel also has a whole optimization reference manual [Intel] (scroll down, it’s all on the same page). The manual helps understand what exactly the CPU is doing.
[Intel] https://www.intel.com/content/www/us/en/developer/articles/t...
Personally, I believe in automated benchmarks that measure end-to-end what is actually important and notify you when a change impacts performance for the worse.
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Managing mutable data in Elixir with Rust
Let's compile it with https://godbolt.org/, turn on some optimisations and inspect the IR (-O2 -emit-llvm). Copying out the part that corresponds to the while loop:
4:
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Free MIT Course: Performance Engineering of Software Systems
resources were extra useful when building deeper intuitions about GPU performance for ML models at work and in graduate school.
- CMU's "Deep Learning Systems" Course is hosted online and has YouTube lectures online. While not generally relevant to software performance, it is especially useful for engineers interested in building strong fundamentals that will serve them well when taking ML models into production environments: https://dlsyscourse.org/
- Compiler Explorer is a tool that allows you easily input some code in and check how the assembly output maps to the source. I think this is exceptionally useful for beginner/intermediate programmers who are familiar with one compiled high-level language and have not been exposed to reading lots of assembly. It is also great for testing how different compiler flags affect assembly output. Many people used to coding in C and C++ probably know about this, but I still run into people who haven't so I share it whenever performance comes up: https://godbolt.org/
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Verifying Rust Zeroize with Assembly...including portable SIMD
To really understand what's going on here we can look at the compiled assembly code. I'm working on a Mac and can do this using the objdump tool. Compiler Explorer is also a handy tool but doesn't seem to support Arm assembly which is what Rust will use when compiling on Apple Silicon.
- 4B If Statements
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Operator precedence doubt
Play around with it in godbolt if you're really curious: https://godbolt.org/
What are some alternatives?
tianocore
C++ Format - A modern formatting library
Essentials-of-Compilation - A book about compiling Racket and Python to x86-64 assembly
rust - Empowering everyone to build reliable and efficient software.
scrcpy - Display and control your Android device
format-benchmark - A collection of formatting benchmarks
sre-interview-prep-guide - Site Reliability Engineer Interview Preparation Guide
papers - ISO/IEC JTC1 SC22 WG21 paper scheduling and management
www.submarinecablemap.com - Comprehensive interactive map of the world's major operating and planned submarine cable systems and landing stations, updated frequently.
rustc_codegen_gcc - libgccjit AOT codegen for rustc
linux-insides - A little bit about a linux kernel
firejail - Linux namespaces and seccomp-bpf sandbox