[filestore configuration]How can I calculate the most suitable number of files in a subdirectory

[dalot wong <dalot.jwongz@xxxxxxxxx>]

May I ask a question?
The default number of files in a subdirectory before splitting into
child directories is between 320 and 640. My server have 256GB
memory,and numbers of core  are 64.How can I calculate the most
suitable number?

thanks