which function calls the ParallelCopy_nowait() , it consumes 58.44 % of cose in my program

[ztdepztdep]

in My program, it consumes about 58% of my cost. how to improeve it.

[WeiqunZhang]

What does your code do besides FillPatchSingleLevel? If the floating point calculation is really cheap, the cost will be dominated by communication.