Intermittent CUDA_ERROR_FILE_NOT_FOUND: file not found errors

[matthiasdiener]

Happens in eager and lazy mode.

Setting CUDA_CACHE_DISABLE=1 or CUDA_CACHE_DIR to a node-local FS does not appear to fix this.

Maybe it is missing an fsync() somewhere in the stack?

See e.g. https://github.com/illinois-ceesd/testing/runs/6662629174?check_suite_focus=true#step:3:3438

*** Running parallel example (2 ranks): ../examples/poiseuille-mpi.py
rank 0: sent all mesh partitions
rank 1: received local mesh (size = 142547)
../examples/poiseuille-mpi.py:178: DeprecationWarning: EagerDGDiscretization is deprecated and will go away in 2022. Use the base DiscretizationCollection with grudge.op instead.
  discr = EagerDGDiscretization(
../examples/poiseuille-mpi.py:178: DeprecationWarning: EagerDGDiscretization is deprecated and will go away in 2022. Use the base DiscretizationCollection with grudge.op instead.
  discr = EagerDGDiscretization(
building face restriction: start
building face restriction: start
building face restriction: done
building face restriction: done
bdry comm rank 0 comm begin
bdry comm rank 1 comm begin
build program: kernel 'einsum3to2_kernel' was part of a lengthy source build resulting from a binary cache miss (0.89 s)
build program: kernel 'einsum3to2_kernel' was part of a lengthy source build resulting from a binary cache miss (0.89 s)
CUDA_ERROR_FILE_NOT_FOUND: file not found
bdry comm rank 0 comm end
ERROR:  One or more process (first noticed rank 1) terminated with signal 6
*** Example ../examples/poiseuille-mpi.py failed.

cc @MTCam

[inducer]

• Does this happen if the pocl kernel cache is not on a networked file system?
• Can we perhaps have pocl check whether the file is there, and if not, have it wait a second or two? (There's a presumption here that this is likely a pocl issue... but I don't know that for sure.)

[MTCam]

• Does this happen if the pocl kernel cache is not on a networked file system?

Setting POCL_CACHE_DIR to a host-local, and even rank-local file does not seem to have an effect on the frequency with which this error occurs. Have tried both with and without these and other cache directory settings - with no apparent change.

This error has become far more frequent with recent code. Currently we don't seem to be able to run any production-relevant driver beyond 2 ranks due to this (or related) errors. Running 4 ranks for combozzle or even a simple mixture case currently will almost certainly get you one (or multiples) of these messages:

CUDA_ERROR_FILE_NOT_FOUND: file not found
CUDA_ERROR_INVALID_IMAGE: device kernel image is invalid
pocl-cuda: failed to generate PTX

[inducer]

The pocl kernel compilation code looks pretty racy:

https://github.com/pocl/pocl/blob/25dd411b0b3f3bd3901d255a7d49bb4f362f6a21/lib/CL/devices/cuda/pocl-cuda.c#L967-L975

(E.g. the existence check races with the write.)

[matthiasdiener]

The pocl kernel compilation code looks pretty racy:

https://github.com/pocl/pocl/blob/25dd411b0b3f3bd3901d255a7d49bb4f362f6a21/lib/CL/devices/cuda/pocl-cuda.c#L967-L975

I think we can't really change the filename of the ptx file (e.g., generate a unique random filename) since that would defeat caching, but maybe wrapping the pocl_ptx_gen and cuModuleLoad operations in a flock might help.

However, this race condition seems to not explain that we still see these errors when running with a rank-local pocl cache.

[MTCam]

I no longer experience this issue since inducer/arraycontext#198. Close?

[matthiasdiener]

I no longer experience this issue since inducer/arraycontext#198. Close?

I think the intermittent errors from the initial message still happen sometimes, right?

[MTCam]

I think the intermittent errors from the initial message still happen sometimes, right?

I have not encountered this error at all (on Lassen) since using:

export LOOPY_NO_CACHE=1
export CUDA_CACHE_DISABLE=1

[inducer]

Are both of those essential? I.e., specifically, can you do without the LOOPY_NO_CACHE=1?

[matthiasdiener]

I think we haven't seen this issue since setting rank-local POCL_CACHE_DIRs. Should we close this?

[MTCam]

Are both of those essential? I.e., specifically, can you do without the LOOPY_NO_CACHE=1?

After not using LOOPY_NO_CACHE for a while, this problem has not cropped back up. But I still have CUDA_CACHE_DISABLE=1 all the time. We better hold on to this issue for just a little while longer. This error may come back. I am not sure it is affected at all by our rank-or-node-local caching strategies.

[matthiasdiener]

pocl/pocl#1480 should have addressed this, closing.