1
GPU workshop cheatsheet
OpenACC guide (PGI flags –acc –ta=nvidia –Minfo=accel)
Kernels Construct
An accelerator kernels construct surrounds loops to be executed on the accelerator, typically as a sequence of
kernel operations.
C
#pragma acc kernels [clause [[,] clause]…] new-line
{ structured block }
Fortran
!$acc kernels [clause [[,] clause]…]
structured block
!$acc end kernels
Any data clause is allowed.
other clauses
if( condition )
When the condition is nonzero or .TRUE. the kernels region will execute on the accelerator; otherwise, it will execute
on the host.
async( expression )
The kernels region executes asynchronously with the host.
Data Construct
An accelerator data construct defines a region of the program within which data is accessible by the accelerator.
C
#pragma acc data [clause[[,] clause]…] new-line
{ structured block }
Fortran
!$acc data [clause[[,] clause]…]
structured block
!$acc end data
Any data
Data Clauses
The description applies to the clauses used on parallel constructs, kernels constructs, data constructs, declare
constructs, and update directives.
copy( list )
Allocates the data in list on the accelerator and copies the data from the host to the accelerator when entering the
region, and copies the data from the accelerator to the host when exiting the region.
copyin( list )
Allocates the data in list on the accelerator and copies the data from the host to the accelerator when entering the
region.
copyout( list )
Allocates the data in list on the accelerator and copies the data from the accelerator to the host when exiting the
region.
create( list )
Allocates the data in list on the accelerator, but does not copy data between the host and device.
present( list )
The data in list must be already present on the accelerator, from some containing data region; that accelerator copy
is found and used.
