Options convosync=direct and mincache=direct while mounting an VxFS for directio

Hi,

I am using VxFS on Solaris 10 with directio by setting convosync=direct and mincache=direct while mounting an VxFS filesystem.

The test result shows that mincache=direct dose help a lot to improve performance, but convosync=direct seems useless. The application doesn't use read/write() with O_SYNC.

By definitions:
"mincache=direct will cause any reads without the O_SYNC flag, or any writes without the O_SYNC flag, VX_DSYNC, VX_DIRECT, and VX_UNBUFFERED caching advisories, to be handled as if the VX_DIRECT caching advisory had been set." and

"convosync=direct will cause any reads or writes with the O_SYNC flag to be handled as if the VX_DIRECT caching advisory had been set. "

My question is:
Is convosync=direct mandatory for VxFS using directio? Thanks.