High iodepth exhibits roughly the same read performance as low iodepth by using Usrbio.

I adopt https://github.com/deepseek-ai/3FS/blob/main/src/lib/api/UsrbIo.md#example-4 to read 20GiB file serially (single thread), I use two different configs:
1. NUM_IOS = 640，BLOCK_SIZE = (32 << 20) with just one hf3fs_submit_ios
2. NUM_IOS = 1, BLOCK_SIZE = (32 << 20) with multiple hf3fs_submit_ios
Both give the roughly the same read performance (about 1.5GiB/s), but I expect above first config should have more high degree of parallelism, so it should have more high read throughput performance.（The entire 3fs system uses the default configuration file）