- (minor issue) async example is artificially limited to 1 thread (the article states that). The issue is comparing 8 OS threads no async to 1 thread async is fundamentally not very useful as long as you didn't pin all threads to the same physical core.. So in general you should compare something async with num_cpus threads vs. num_cpus*X OS threads. Through this wouldn't have been that useful in this example without pinning the tokio async threads to CPUs to forcefully highlight the page issue, and doing it is bothersome so I wouldn't have done so either.
- (bigger issue) The singled thread async "traditional IO" example is NOT single threaded. Async _file_ IO anything between not a thing or very bad in most OSes hence most async engines including tokio do file IO in worker threads. This means the "single threaded" conventional IO async example is running 8 threads for reading IO and one to "touch the buffer" (i.e. do hardly anything).
To be clear the single threaded not being single threaded issue isn't discrediting the article, the benchmarks still show the problem it's that the 8 threaded conventional and 1 threaded async conventional are accidentally basically both 8 thraded.