[slurm-users] GPU / cgroup challenges

[R. Paul Wiegand]

I dug into the logs on both the slurmctld side and the slurmd side.
For the record, I have debug2 set for both and
DebugFlags=CPU_BIND,Gres.

I cannot see much that is terribly relevant in the logs.  There's a
known parameter error reported with the memory cgroup specifications,
but I don't think that is germane.

When I set "--gres=gpu:1", the slurmd log does have encouraging lines such as:

[2018-05-02T08:47:04.916] [203.0] debug:  Allowing access to device
/dev/nvidia0 for job
[2018-05-02T08:47:04.916] [203.0] debug:  Not allowing access to
device /dev/nvidia1 for job

However, I can still "see" both devices from nvidia-smi, and I can
still access both if I manually unset CUDA_VISIBLE_DEVICES.

When I do *not* specify --gres at all, there is no reference to gres,
gpu, nvidia, or anything similar in any log at all.  And, of course, I
have full access to both GPUs.

I am happy to attach the snippets of the relevant logs, if someone
more knowledgeable wants to pour through them.  I can also set the
debug level higher, if you think that would help.


Assuming upgrading will solve our problem, in the meantime:  Is there
a way to ensure that the *default* request always has "--gres=gpu:1"?
That is, this situation is doubly bad for us not just because there is
*a way* around the resource management of the device but also because
the *DEFAULT* behavior if a user issues an srun/sbatch without
specifying a Gres is to go around the resource manager.



On Tue, May 1, 2018 at 8:29 PM, Christopher Samuel <chris at csamuel.org> wrote:
> On 02/05/18 10:15, R. Paul Wiegand wrote:
>
>> Yes, I am sure they are all the same.  Typically, I just scontrol
>> reconfig; however, I have also tried restarting all daemons.
>
>
> Understood. Any diagnostics in the slurmd logs when trying to start
> a GPU job on the node?
>
>> We are moving to 7.4 in a few weeks during our downtime.  We had a
>> QDR -> OFED version constraint -> Lustre client version constraint
>> issue that delayed our upgrade.
>
>
> I feel your pain..  BTW RHEL 7.5 is out now so you'll need that if
> you need current security fixes.
>
>> Should I just wait and test after the upgrade?
>
>
> Well 17.11.6 will be out then that will include for a deadlock
> that some sites hit occasionally, so that will be worth throwing
> into the mix too.   Do read the RELEASE_NOTES carefully though,
> especially if you're using slurmdbd!
>
>
> All the best,
> Chris
> --
>  Chris Samuel  :  http://www.csamuel.org/  :  Melbourne, VIC
>