Re: OpenACC-Library-Interoperability

[Cesar Philippidis <cesar_philippidis@mentor.com>]

On 08/29/2016 08:38 AM, Vikram Singh wrote:

> z from the cublasdgemm call gives 0 everywhere, unlike the actual
> dgemm call. The first line of output is
> 
>  ** On entry to DGEMM  parameter number 1 had an illegal value

Check the documentation for cublas. You may not be calling that function
with the proper arguments.

> In addition, I looked at your test case. You do not do
> 
>  !$acc update self(y)
> 
> Does that mean that the host variable is automatically updated in gfortran.

The host_data clause tells the compiler to use variables that have
already been mapped onto the accelerator via acc data or acc enter enter
data. You need to use the data directives to actually move the data as
appropriate. In host_data-2.f90 example, the value of 'y' was going to
be copyied out by the acc data region, so there was no need to use acc
update host.

You only need to use the update directive if you want to retain that
data on the accelerator.

Cesar