Default compute dimensions (runtime)

[Nathan Sidwell]

On 02/03/16 11:10, Alexander Monakov wrote:
> Hello,
>
> On Wed, 3 Feb 2016, Nathan Sidwell wrote:
>> 1) extend the -fopenacc-dim=X:Y:Z syntax to allow '-' indicating a runtime
>> choice.  (0 also indicates that, but I thought best to have an explicit syntax
>> as well).
>
> Does it work when the user specifies one of the dimensions, so that references
> to it are subject to constant folding and VRP, but leaves some other dimension
> unspecified, and when eventually GOMP_OPENACC_DIM is parsed at runtime, the
> runtime-specified value of the first dimension is different from what the
> compiler saw, invalidating all folding and propagation?

You can only override at runtime those dimensions that you said you'd override 
at runtime when you compiled your program.

> I don't see why you say that because cuDeviceGetAttribute provides
> CU_DEVICE_ATTRIBUTE_WARP_SIZE, CU_DEVICE_ATTRIBUTE_MAX_THREADS_PER_BLOCK,
> CU_DEVICE_ATTRIBUTE_MAX_GRID_DIM_X (which is not too useful for this case) and
> cuFuncGetAttribute that allows to get a per-function thread limit.  There's a
> patch on gomp-nvptx branch that adds querying some of those to the plugin.

thanks.  There doesn't appear to be one for number of physical CTAs though, right?

nathan