munrocket

WGSL Noise Algorithms

Good and fast integer hash

// https://www.pcg-random.org/
fn pcg(n: u32) -> u32 {
    var h = n * 747796405u + 2891336453u;
    h = ((h >> ((h >> 28u) + 4u)) ^ h) * 277803737u;
    return (h >> 22u) ^ h;
}

HenningTimm

Memory profiling Rust code with heaptrack in 2019

I recently ran into a classic case of "our code is using way more memory than it should". So I took my first dive into memory profiling Rust code. I read several posts about this, including the following

• KodrAus' gist on profiling rust
• This reddit thread
• Brendan D. Gregg's post about memory flamegraphs
• Bradlee Speice's A Case Study in Heaptrack

htfy96

C++ has a lot of dark corners. Unfortunately, sometimes we need to allow inexperienced developers to write some C++ code to meet the deadline. The intersection of the two cases often makes things worse: programmers used to delegate memory management to garbage collection tend to throw off new everywhere in the source, and those stuck with compile error will use every evil hack to get around with it. Code review is a feasible way to ensure code quality in this case, but a better choice is to restrict them into a relatively safe subset of the language.

In this article, I will show how to use clang-query and a simple script to restrict some unsafe behaviors in unsafe block/namespace using simple commands:

#include "common.hpp"

struct X {
    int f: 2; // error: use of bit field without enclosing Unsafe
};

lava

Hello, world!

Please explain in detail what will happen if the following program is executed:

#include <iostream>

int main() {
    std::cout << "Hello, world!" << std::endl;
}

jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD