GRPO config: what's the reason that the global batch size must be divisible by the number of generations?

[MrDoghead]

I found that the parameter num_generations: Number of generations per prompt to sample. The global batch size (num_processes * per_device_batch_size) must be divisible by this value.

Does anyone know why?

[AIR-hl]

Same problem ! @qgallouedec

my settings: num_generations=8, per_device_train_batch_size=1, gradient_accumulation_steps=8

ValueError: The global train batch size (1 x 1) must be evenly divisible by the number of generations per prompt (8). Given the current train batch size, the valid values for the number of generations are: [].

[AIR-hl]

I found that the parameter num_generations: Number of generations per prompt to sample. The global batch size (num_processes * per_device_batch_size) must be divisible by this value.

Does anyone know why?

@MrDoghead Here is reason: #2776 (comment)