Benchmark of the filesystems performing opening files.

I was going to use 'open()' to eliminate the stdio overhead, but it's actually comparatively tiny for the case of opening a file, and it made the code slightly more portable (lookin' at you win32).

cmake -DCMAKE_BUILD_TYPE=Release cmake --build . --target SimpleBench

and then run the SimpleBench executable.

This will create ~1000 one-line text files in the current directory and then repeatedly open them, capturing the timing, and then deleting them.

Output on a high-end 2019 i7 on Samsung nvme drive/Windows:

Iteration Stats (4096 files): min=56ms, avg=59ms, p90=62ms, p95=63ms, p99=68ms, max=77ms
Per File: 14411ns

Output from an Ubuntu 18.04 VM on an Intel NUC with a SATA 2 SSD:

Iteration Stats (4096 files): min=10ms, avg=11ms, p90=12ms, p95=13ms, p99=15ms, max=18ms
Per File: 2786ns

Output from an Ubuntu 19.04 Linux machine on an EVO SSD:

Iteration Stats (4096 files): min=2ms, avg=4ms, p90=4ms, p95=5ms, p99=6ms, max=7ms
Per File: 914ns