Disk read operation size of the qbittorrent torrent client?

[slrslr]

qbt 4.3.3, Linux

Hello, where can i see how much data qbt is usually reading per one disk read request when seeding torrents. I want to know so i can setup the filesystem record size appropriately.

I know in Advanced settings tab is https://www.libtorrent.org/reference-Settings.html#send_buffer_watermark
it says:
if the send buffer has fewer bytes than send_buffer_watermark, we'll read another 16 kiB block onto it. If set too small, upload rate capacity will suffer. If set too high, memory will be wasted
what it mean? Is it up to date that qbt will always read in 16k chunks and add these into RAM based "Send buffer watermark", In my case:
Send buffer watermark 2048KiB
Send buffer low watermark: 512kiB
Send buffer watermark factor 100%
?