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Memory Subsystem Optimizations

48 points by mfiguiere

by jeffbee

3 subcomments

I find this site interesting because of its mixture of good topic choice and inaccurate details. I think it's generated by LLMs.
Specifically catching my eye in this collection of articles is the highly misleading one about huge pages. All recent Linux distributions have THP set to "madvise" by default. Many programs exploit THP automatically, including any Go program and any JVM program with a flag set. The tcmalloc shared library that comes with Ubuntu is probably the single worst way to experience huge pages. Mi-malloc is the better choice if you must preload a library, but there are even better choices. Explicit huge pages are little-used because managing them is annoying. Finally, latest Linux kernels have features called "folios"and "mTHP" that make THP even smoother.

by grayxu

0 subcomment

While this guide covers roughly 80% of the material, it remains a high-level overview that lacks depth. I can't confirm if it was LLM-generated, but the content is undeniably superficial. Real-world production environments are far more complex; for instance, despite other users mentioning hugepages and TLB, there is no discussion of critical issues like TLB shootdown.

by adsharma

0 subcomment

18 blog posts and very limited mention of NUMA and HT?
https://adsharma.github.io/more-performance-hints/

by matu3ba

0 subcomment

The blog looks nice, especially having simple to understand numbers. To me the memory subsystem articles are missing the more spicy pieces like platform semantics, barriers, de-virtualization (latter discussed in an article separate of the series). In the other articles I'd also expect debugging format trade-offs (DWARF vs ORC vs alternatives), virtualization performance and relocation effects briefly discussed, but could not find them. There are a few C++ article missing: 1. cache-friendly structures in C++, because standard std::map etc are unfortunately not written to be cache-friendly (only std::vector and std::deque<T> with high enough block_size), ideally with performance numbers, 2. what to use for destructive moves or how to roll your own (did not make it into c++26).