GRPO loss #454
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GRPO loss #454
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rafapi
reviewed
Jan 20, 2026
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| # Policy loss | ||
| # TODO: advantages or rewards? | ||
| log_ratio_old = torch.exp(target_logprobs - old_logprobs) |
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this would read better as ratio_new_old = torch.exp(target_logprobs - old_logprobs)
rafapi
reviewed
Jan 20, 2026
| target_logprobs = torch.gather(logprobs, dim=2, index=labels.unsqueeze(2)).squeeze(2) | ||
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| # Policy loss | ||
| # TODO: advantages or rewards? |
rafapi
reviewed
Jan 20, 2026
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| # TODO: tokens_weights = 1/batch_size ? | ||
| # TODO: Reduce loss? |
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need to sum over tokens and apply mask
rafapi
reviewed
Jan 20, 2026
| torch.clamp(log_ratio_old, 1 - self.epsilon_low, 1 + self.epsilon_high) * advantage, | ||
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| # TODO: tokens_weights = 1/batch_size ? |
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i think so, we do that for the simple case
rafapi
reviewed
Jan 20, 2026
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| # TODO: tokens_weights = 1/batch_size ? | ||
| # TODO: Reduce loss? | ||
| loss = loss / batch_size # 1 x (BxL) x 1 |
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loss = -loss - we want to maximise the objective
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✨ Description