Re: [Starpu-devel] automatic RAM allocation and CUDA worker issue

[Kevin Juilly <kevin.juilly@eolen.com>]

Hello,

I tested the starpu-1.2 branch with our test case, and the problem does 
not occur anymore.

Regards,
Kevin Juilly

Le 30 novembre 2017 à 11 h 33, Olivier Aumage a écrit :
> Hello,
>
> Thanks for the bug report. Revisions r22589 for the "starpu-1.2/" branch and r22590 for 
> the "trunk/" branch should fix the problem.
>
> Best regards,
> --
> Olivier
>
> > Le 13 nov. 2017 à 14:28, Kevin Juilly <kevin.juilly@eolen.com> a écrit :
> >
> > Hello,
> >
> > On a node with a GPU, if a program asks for more memory than the GPU got, the 
> > data are registered with -1 as home_node and  all but the GPU worker are 
> > disabled, StarPU 1.2 will abort on an assert (see assert.log) even if the 
> > need of any task is well under the size of the GPU memory.
> >
> > The problem doesn't seem to occur when STARPU_PREFETCH=0.
> >
> > A reproducer is attached. This code allocate a lot of square matrices and 
> > start task on them. The tasks themselves do not do any work and are only 
> > cuda_func, their only purpose is to force memory management to occur on the 
> > GPU
> >
> > The program takes two optionnal parameters:
> > - the size of the matrices
> > - the number of matrices
> > When no argument are given, it will try to allocate enough matrices to use 3 
> > times the size of the GPU memory. The assertion doesn't occur when not 
> > allocating enough, even if it is more than the size of the GPU memory.
> >
> > This reproduces the memory behaviour of the test case that triggered the bug.
> >
> > Also attached you'll find : a config.log extract and the list of StarPU 
> > environment variables used.
> >
> >
> > As a note, the same case produced incorrect behaviour with StarPU 1.1. In 
> > this case the worker was stuck (it seems) in an infinite loop inside 
> > _starpu_fetch_task_input (calling function to try to free memory). I haven't 
> > been able to reproduce it recently and have no idea why.
> >
> > Regards,
> > Kevin Juilly
> > AS+ groupe Eolen
> > <assert.log><alloc_assert.c><extract_config.log><env_repro.txt>_______________________________________________
> > Starpu-devel mailing list
> > Starpu-devel@lists.gforge.inria.fr
> > https://lists.gforge.inria.fr/mailman/listinfo/starpu-devel