4 ms·

I'm pretty sure that even at their slowest, syscalls aren't going to match IO overhead. It's not like the mkfile is CPU bound.

• mpweiher 10y ago
  The point of the article is that I was also "pretty sure" about exactly that, and advances in hardware performance meant I was wrong... 2GB/s is pretty damn fast, 0.5 nanoseconds per byte.
  • cbsmith 10y ago
    That's not what the article showed. It showed that synchronous IO latency was the limiting factor. By arranging your IOs into little 512-byte chunks, you don't make it terribly easy for the filesystem to efficiently use the underlying device --not surprising, given that it doesn't even want to work in 512 byte sectors, and operates more efficiently with lots of a parallel io operations.
    • mpweiher 10y ago
      OS X does write-coalescing.
      • cbsmith 10y ago
        You can't write coalesce IO operations that haven't been called yet.