James Mitchell

Principal Software Engineer at @shgames | Works on @callofduty | Posts on C++, low level optimisations and security.

Opinions are my own.

[James Mitchell @reductor]

My talk at @GCAPConf on Expert Level Debugging that shows how to manually unwind corrupted call stacks using stack memory and registers is now online.
https://t.co/A9UnTpGGmd

[James Mitchell @reductor]

@CPPAlliance The fact that make_hazard_ptr can allocate to me makes this a non-starter. If I am writing lock free code its often because of performance, I dont want surprise allocations that could cripple performance.

[Meeting C++ @meetingcpp]

Take the C++ performance Quiz!
https://t.co/uLqIumcfHd
#cpp
#cplusplus

[James Mitchell @reductor]

All feedback is welcome, there is bound to be some bugs in the questions/answers

[James Mitchell @reductor]

Sharing my fun side project: A C++ Performance Quiz

Covers algorithms to low-level gotchas, with Compiler Explorer links to see the generated machine code. Built for fun & intuition, not to judge skill!

https://t.co/DldHaJunM4

(Personal project, independent of employer)

[James Mitchell @reductor]

@notreaIlyjohn @ChShersh That would probably be worse for any text that is heavily ASCII as you introduce a loop carried data dependency, as each loop iteration depends on the data of all previous iterations, where the branch does not so if it predicts correctly it can be significantly faster.

[James Mitchell @reductor]

@abdimoalim_ If it was doubly linked you could go from the head and tail simultaneously and get even better throughput, with less reliance on the nodes being consecutive and potential undefined behaviour.

[James Mitchell @reductor]

@ID_AA_Carmack My Twitter for you page is full of American right wing politics, I am an Australian game developer, the algorithm is broken. Blue checkmarks ensure visibility and why would I pay for a platform like that? Just look at the responses need to scroll heaps to see one non-blue check

[James Mitchell @reductor]

@Cali_burbia @MickWest Is it possible that the pilot suffered from Sensory Illusion? An easy way to test is see if you can reproduce the same thing with glare, if you can it seems like a plasuable explanation over something extraordinary.
https://t.co/gWsWCioK55

[James Mitchell @reductor]

Playing with AI slop for a non-existant CPU performance tool, now I wish it was real.

[James Mitchell @reductor]

@Bias_Zebra @lemire What a crazy assumption, I dont want everyone poor, I want incentive for people to do things, I just dont want extreme wealth inequality. I am for capitalism with reasonable taxes and suppprt systems for everyone. A rich country shouldnt have starving homeless kids.

[James Mitchell @reductor]

@britcatala @lemire Inflation is caused by many things, doubling everyones income and 10x for the rich is essentially printing money. However in this case the inflation would be part of the wage-price spiral which is a macroeconomics theory where rising prices lead to higher prices.

[James Mitchell @reductor]

@iyoushetwt And probably are OOP, time to learn OOP?

[James Mitchell @reductor]

@rajaboys @iyoushetwt I used to always use EditPlus, just checked its still around and last updated today.

[James Mitchell @reductor]

@benjoffe What is your use case? It seems strange that this would be a bottleneck

[James Mitchell @reductor]

My @GCAPConf talk on Lessons Learned from two decades of writing bad code has gone up on YouTube.

I introduce a new way to iterate Linked Lists that is twice as fast as the traditional approach without changing the data structure.

https://t.co/OOvCtPyyiM

[James Mitchell @reductor]

@geofflangdale I am conflicted if its good/bad to recommend his content, he is knowledgable about many things he discusses and has some good content for people to learn from in an area that there isnt much, then some is strawman arguments to his followers that dont see the strawmaning like OOP

[James Mitchell @reductor]

@feliperybas @valigo Its really isnt a must watch, its a strawman argument. With a contrived example and benchmark which will intentionally make the "clean code" slow. Combined with saying clean code is something that it is not, just like OOP often gets misrepresented as something it is not.

[James Mitchell @reductor]

@unclebobmartin People who lookup components by entity id frequently on ECS and think thats how you use it are often using it incorrectly and can end up just as slow as naieve OOP.

[James Mitchell @reductor]

@unclebobmartin I dont hate OOP you can write fast OOP just like you can write slow ECS code, neither are magic bullets. SIMD use cases are small, arrays are the powerhouse you aim to do bulk operations on one or more arrays, helping hardware prefetching, less load data dependencies, etc.