Can I limit the distributed GPUs?

[bermeitinger-b]

I'm using your script on a machine with 16 GPUs. For my tasks, I want specific GPUs to not be used or rather select which GPUs are used.

For example, I want GPUs 0-8 to be available to ts but 9-15 be left alone. Is this something that can be done?

[justanhduc]

Hi @bermeitinger-b. If I understand it correctly then ts is not possible to auto select GPUs from a subset as it uses NVML, which will discover all possible GPUs. You can try to use -g in this case to manually specify the GPU ID. May I ask about your specific use case why you want to do that?

[bermeitinger-b]

Thanks, let me clarify.

I'm running experiments on a machine that has 16 GPUs. I'm running a lot of tasks and use ts with -S 24 to schedule the tasks such that they are distributed among the GPUs. That is working very well.
But there are other users on the machine that also require access to the GPUs. So, I want to limit my user's capabilities to specific GPUs (e.g. 0-8). (Of course with a reduced -S)

Fixing which job runs on which GPU with -g would make ts useless in my case. If I would know beforehand which task should run on which GPU, I could use simple shell scripts for each GPU with the tasks one after another, right?
That's the beauty of ts: As soon as one tasks finishes, it will check which GPU is free and run it there, so there are no idle GPUs.

[justanhduc]

I got it. I sometimes got complained about selecting GPUs randomly too. I guess limiting the visibility of GPUs to ts can be useful. If you don't mind waiting I can work on it in a few days.

[justanhduc]

For now you can use -g together with -D or -W to queue jobs for a specific GPU ID.

[justanhduc]

Hi @bermeitinger-b. I prototyped this feature in this branch. Basically, you can set an env var like TS_VISIBLE_DEVICES=0,1,2,3,4,5,6,7 before starting ts for the first time. If ts is already up, you can use the flag --setenv TS_VISIBLE_DEVICES=0,1,2,3,4,5,6,7 to set the env var. Please see the Readme for more details.

[bermeitinger-b]

Thank you very much. I tried the branch and it seems it working exactly as intended.

[bermeitinger-b]

Does this new limit also the number of concurrent tasks?

My current approach to use GPUs 0-8 with 16 concurrent jobs (so 2 per GPU) would be to

1. ts -K (to make sure)
2. TS_VISIBLE_DEVICES=0,1,2,3,4,5,6,7 ts -S 16
3. for i in $(seq 1 16); do ts -G 1 ./job.sh; done

However, I'm not seeing 16 concurrent jobs but only 8. (The jobs are small enough that the 90% full-rate is not reached.)

[justanhduc]

Hi @bermeitinger-b. This is intended. -G queues jobs until there is free GPU to run. A GPU is deemed free if its memory is more than 90% free. The only solution for running multiple processes on a GPU is using -g so far.
I have thought about having an option to manually set the free percentage value but never materialized. If you could wait a couple of days, I can make a quick patch for this option.

[justanhduc]

Hi @bermeitinger-b. You can pull to get the new features. To run multiple processes in a GPU, you can set the free memory threshold (in percentage) appropriately via ts --set_gpu_free_perc.