Unbuffered I/O Can Make Your Rust Programs Much Slower

1. Use strace and perf to count how many syscalls were invoked.
2. Yeah, Rust actually supports file I/O without buffer. It's may more simple in some situtations

Conclusion

In this post¹, we saw that:

• System calls in Linux are slower than regular functions
• Issuing too many syscalls can have very negative effects on run-time performance
• By using BufReader and BufWriter, we can amortize the cost of syscalls
• Even experienced programmers can miss these issues
• We can use strace and awk to find if and where unbuffered I/O happens in our programs