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sglang/python/sglang/jit_kernel/tests/test_renorm.py
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Python

# Adapted from https://github.com/flashinfer-ai/flashinfer/blob/main/tests/test_sampling.py
# and /sgl-workspace/sglang/sgl-kernel/tests/test_sampling.py
import sys
import pytest
import sgl_kernel
import torch
from sglang.test.ci.ci_register import register_cuda_ci
register_cuda_ci(est_time=6, suite="stage-b-kernel-unit-1-gpu-large")
register_cuda_ci(est_time=120, suite="nightly-kernel-1-gpu", nightly=True)
@pytest.mark.parametrize("batch_size", [1, 99, 989])
@pytest.mark.parametrize("vocab_size", [111, 32000, 128256])
@pytest.mark.parametrize("k", [10, 100, 500])
def test_top_k_renorm_probs(batch_size, vocab_size, k):
"""Test top_k_renorm_probs kernel for correctness.
This test validates that the kernel correctly:
1. Identifies the top-k probabilities
2. Masks out non-top-k values
3. Renormalizes the remaining probabilities to sum to 1
"""
if k > vocab_size:
pytest.skip("k should be less than vocab_size")
torch.manual_seed(42)
pre_norm_prob = torch.rand(batch_size, vocab_size, device="cuda:0")
normalized_prob = pre_norm_prob / pre_norm_prob.sum(dim=-1, keepdim=True)
sorted_prob, _ = torch.sort(normalized_prob, descending=True)
pivot = sorted_prob[:, k - 1]
mask = (normalized_prob >= pivot.unsqueeze(-1)).int()
renorm_prob_ground_truth = normalized_prob.clone()
renorm_prob_ground_truth[mask == 0] = 0
renorm_prob_ground_truth = renorm_prob_ground_truth / renorm_prob_ground_truth.sum(
dim=-1, keepdim=True
)
renorm_prob = sgl_kernel.top_k_renorm_prob(normalized_prob, k)
for i in range(batch_size):
torch.testing.assert_close(
renorm_prob_ground_truth[i],
renorm_prob[i],
rtol=1e-3,
atol=1e-3,
)
@pytest.mark.parametrize("batch_size", [1, 99, 989])
@pytest.mark.parametrize("vocab_size", [111, 32000, 128256])
@pytest.mark.parametrize("p", [0.1, 0.5, 0.9])
def test_top_p_renorm_probs(batch_size, vocab_size, p):
"""Test top_p_renorm_probs kernel for correctness.
This test validates that the kernel correctly:
1. Computes the cumulative probability distribution
2. Identifies tokens in the top-p threshold
3. Masks out tokens outside the threshold
4. Renormalizes the remaining probabilities to sum to 1
"""
torch.manual_seed(42)
pre_norm_prob = torch.rand(batch_size, vocab_size, device="cuda:0")
normalized_prob = pre_norm_prob / pre_norm_prob.sum(dim=-1, keepdim=True)
sorted_prob, indices = torch.sort(normalized_prob, descending=False)
cdf = torch.cumsum(sorted_prob, dim=-1)
mask = torch.zeros(batch_size, vocab_size, dtype=torch.int32, device="cuda:0")
mask.scatter_add_(1, indices, (cdf >= (1 - p)).int())
renorm_prob_ground_truth = normalized_prob.clone()
renorm_prob_ground_truth[mask == 0] = 0
renorm_prob_ground_truth = renorm_prob_ground_truth / renorm_prob_ground_truth.sum(
dim=-1, keepdim=True
)
renorm_prob = sgl_kernel.top_p_renorm_prob(normalized_prob, p)
torch.testing.assert_close(
renorm_prob_ground_truth,
renorm_prob,
rtol=1e-3,
atol=1e-3,
)
if __name__ == "__main__":
sys.exit(pytest.main([__file__]))