Re: [Starpu-devel] Implementation question regarding output type

[Johan Mazel <johan.mazel@gmail.com>]

Thank you very much for your answer.

Is this new section called "7.1.7 Data Interface with Variable Size" in the 3rd chapter in http://starpu.gforge.inria.fr/doc/starpu.pdf? Or did I miss something? Or is not online yet?

I will take a look at tests/datawizard/variable_size.c, it looks similar to what I want to do.

Thank you very much again.

Johan

Le ven. 20 déc. 2019 à 17:19, Samuel Thibault <samuel.thibault@inria.fr> a écrit :

Hello,

Johan Mazel, le jeu. 19 déc. 2019 14:02:11 +0100, a ecrit:
> This is quite slow because I guess that StarPU has to transfer back all the
> result vectors to the RAM.

Yes.

> I identified two possible solutions :
> * Define a new data interface ([1]http://starpu.gforge.inria.fr/doc/html/

I don't think this will be needed

> * Use the CSR data interface.

That seems overkill :)

> Which one of these two methods looks do you think is the most appropriate for
> my use case? Do you know any examples that use a similar method?

I believe you can just use vectors, by reallocating it during the task.
I have now added a "Changing the size of a data" section in the StarPU
handbook. Basically the bits are shown in the kernel() function in
tests/datawizard/variable_size.c: you just reallocate the data buffer
and fix the size. When StarPU brings back the data to the main memory,
it will only have to transfer that piece.

Samuel