Re: [Starpu-devel] initialised SCRATCH buffer

[Xavier Lacoste <xavier.lacoste@inria.fr>]

Le 05/01/2012 10:58, Samuel Thibault a écrit :
> Xavier Lacoste, le Thu 05 Jan 2012 10:33:44 +0100, a écrit :
> > I would like StarPU to build the array using a function of the codelet
> > arguments at the same time he moves data to the executing device.
> Do you mean that the initialization value needs to depend on the
> parameters of the task? Can't the codelet do the initialization itself
> in such case, since it'll have to be done for each task anyway?
>
> What we were planning to implement was only a way to initialize the
> scratch buffer when it is allocated, i.e. once for good and not once for
> each task (unless the buffer gets evicted due to low memory conditions).
>
> Samuel

Yes this is what I mean this array depends on parameters of the task.
It is build from the bloc number and the whole sparse matrix structure 
which are given through cl->args.
The bloc number is on the computing device but the sparse matrix is just 
a pointer to the data and the GPU can't see what is pointed to as it is 
not copied.

Yes I could build the array in my codelet using my cl->args, then send 
it to the GPU.
But that data transfer may be covered by computation if it was performed 
at the same time data are copied to device.
And I wanted to let StarPU  manage all data transfer.

Xavier.