CppCon
7 HN recommenders · recommended in 11 months, 2014–2024
1:13:41 · 235K views · Oct 21, 2014
Chandler Carruth's CppCon 2014 talk on writing fast C++, explaining why data structure choice and memory layout matter more than clever algorithms. It covers why standard containers like unordered_map perform poorly on modern CPUs.
A perennial recommendation for anyone learning performance optimization, cited whenever hash tables, cache behavior or STL containers come up.
15 comments from Hacker News
There are many things in the standard C++ library which are named incorrectly (std::string), awkwardly (std::unordered_map) and and implemented inefficiently from the perspective of modern CPUs (same std::unordered_map, which uses linked list for the underlying hash table buckets). See the great talk on CppCon 2014 about those issues - this video .
Strongly agree. That's perhaps less true for the software I work on these days (lapack), but I've seen that so many times over my career. I'm also a big fan of "Efficiency with Algorithms, Performance with Data Structures" by Chandler Carruth at CppCon 2014. this video
Here's a few: - "Tuning C++: Benchmarks, and CPUs, and Compilers! Oh My!" [LINK] - "Understanding Compiler Optimization" [LINK] - "Optimizing the Emergent Structures of C++" [LINK] - "Efficiency with Algorithms" this video The first one is really good if you've never benchmarked anything in a Linux environment. Or if you otherwise want to learn how to investigate how C++ gets turned into machine code.
Also, those allocations imply linked, rather than contiguous, data structures, which (often? always?) imply poor cache interaction, which is a major source of inefficiency. Would love some more perspectives on this, as I've just watched a couple cppcon talks ([0], [1]) and I'm feeling a bit drunk on the kool-aid. [0]: this video [1]: [LINK]
Chandler Carruth's CPPCon talk [0] this year was also great (surprisingly, as I had a fairly low opinion of most of the others). It wasn't better than Mike Acton's [1], but I suspect that it was more actionable for most devs. [0] this video [1] [LINK]