Index reorganization runs slower with async IO

Hello,

We are running into performance issue where we could not understand the reason where we turned on async IO on by setting these two parameters:

disk_asynch_io=true

filesystemio_options=setall

Overall performance is much better especially in log writing except one process that does index reorganization that is 2-3 times slower.

Changed to filesystemio_options=async without direct IO and perrormance is almost back to orginal.

database server: 19.25

server: REHL 7

Based on some documents, direct IO should be more efficient, not the result is opposite.

Looking for suggestions on this issue.

Thanks

Larry