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

[Olivier Aumage <olivier.aumage@inria.fr>]

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>_______________________________________________
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