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(fix) fix rms_norm op #946

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Merged
hiworldwzj merged 1 commit into from
Jun 30, 2025
Merged

(fix) fix rms_norm op #946

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2 changes: 1 addition & 1 deletion lightllm/models/llama/triton_kernel/rmsnorm.py
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Original file line number Diff line number Diff line change
Expand Up @@ -56,7 +56,7 @@ def rmsnorm_forward(x: torch.Tensor, weight, eps, out=None):
if N > BLOCK_SIZE:
raise RuntimeError("This layer norm doesn't support feature dim >= 64KB.")
# heuristics for number of warps
num_warps = min(max(BLOCK_SIZE // 256, 1), 8)
num_warps = min(max(BLOCK_SIZE // 256, 1), 4)
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@gemini-code-assist gemini-code-assist bot Jun 30, 2025

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medium

The PR title suggests this change is a fix. It would be very helpful for future maintenance to add a brief inline comment explaining why the maximum number of warps is capped at 4. This provides context for why this specific value was chosen, for example, if it addresses a performance or stability issue on certain hardware.

Suggested change
num_warps = min(max(BLOCK_SIZE // 256, 1), 4)
num_warps = min(max(BLOCK_SIZE // 256, 1), 4) # Capped at 4 for performance/stability reasons

num_warps = triton.next_power_of_2(num_warps)
if BLOCK_SIZE > 16384:
BLOCK_SIZE = 16384
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