Use pinned memory for asynchronous sampling metadata transfers (#39777)

Co-authored-by: Xinyuan Tong <xinyuantong.cs@gmail.com>
Co-authored-by: hnyls2002 <lsyincs@gmail.com>
This commit is contained in:
Yuxuan Zhang
2026-09-20 15:31:31 -07:00
committed by GitHub
co-authored by Xinyuan Tong hnyls2002
parent 95521da18d
commit f31a7bd45c
7 changed files with 245 additions and 24 deletions
@@ -18,7 +18,7 @@ from sglang.srt.model_executor.runner_utils.pool import (
graph_pool_borrow_largest_run,
)
from sglang.srt.runtime_context import get_exec
from sglang.srt.utils.common import async_d2h
from sglang.srt.utils.common import async_d2h, is_pin_memory_available
if TYPE_CHECKING:
from sglang.srt.layers.logits_processor import LogitsMetadata, LogitsProcessorOutput
@@ -151,15 +151,16 @@ def get_token_ids_logprobs_raw(
no_copy_to_cpu: bool = False,
):
vals, idxs = [], []
pin_memory = is_pin_memory_available(logprobs.device)
if stage == LogprobStage.DECODE:
for i, token_ids in enumerate(token_ids_logprobs_list):
if token_ids is None:
vals.append([])
idxs.append([])
else:
token_ids_tensor = torch.tensor(token_ids, dtype=torch.long).to(
logprobs.device, non_blocking=True
)
token_ids_tensor = torch.tensor(
token_ids, dtype=torch.long, pin_memory=pin_memory
).to(logprobs.device, non_blocking=True)
row = logprobs[i, token_ids_tensor]
vals.append(row if no_copy_to_cpu else row.tolist())
idxs.append(token_ids)
@@ -178,9 +179,9 @@ def get_token_ids_logprobs_raw(
idxs.append([])
pt += pruned_len
continue
token_ids_tensor = torch.tensor(token_ids, dtype=torch.long).to(
logprobs.device, non_blocking=True
)
token_ids_tensor = torch.tensor(
token_ids, dtype=torch.long, pin_memory=pin_memory
).to(logprobs.device, non_blocking=True)
pos_logprobs = logprobs[pt : pt + pruned_len, token_ids_tensor]
vals.append(pos_logprobs if no_copy_to_cpu else pos_logprobs.tolist())
idxs.append([token_ids for _ in range(pruned_len)])
@@ -1,6 +1,7 @@
import torch
from sglang.srt.sampling.penaltylib.orchestrator import _BatchedPenalizer
from sglang.srt.utils.common import is_pin_memory_available
class BatchedFrequencyPenalizer(_BatchedPenalizer):
@@ -15,6 +16,7 @@ class BatchedFrequencyPenalizer(_BatchedPenalizer):
)
def _prepare(self):
pin_memory = is_pin_memory_available(self.orchestrator.device)
self.cumulated_frequency_penalties = torch.zeros(
(len(self.orchestrator.reqs()), self.orchestrator.vocab_size),
dtype=torch.float32,
@@ -28,9 +30,11 @@ class BatchedFrequencyPenalizer(_BatchedPenalizer):
for req in self.orchestrator.reqs()
],
dtype=torch.float32,
device=self.orchestrator.device,
pin_memory=pin_memory,
)
).unsqueeze_(1)
.to(self.orchestrator.device, non_blocking=True)
.unsqueeze_(1)
)
def _cumulate_output_tokens(self, output_ids: torch.Tensor):
self.cumulated_frequency_penalties.scatter_add_(
@@ -1,6 +1,7 @@
import torch
from sglang.srt.sampling.penaltylib.orchestrator import _BatchedPenalizer
from sglang.srt.utils.common import is_pin_memory_available
class BatchedMinNewTokensPenalizer(_BatchedPenalizer):
@@ -14,15 +15,21 @@ class BatchedMinNewTokensPenalizer(_BatchedPenalizer):
)
def _prepare(self):
self.min_new_tokens = torch.tensor(
data=[
req.sampling_params.min_new_tokens for req in self.orchestrator.reqs()
],
dtype=torch.int32,
device=self.orchestrator.device,
).unsqueeze_(1)
pin_memory = is_pin_memory_available(self.orchestrator.device)
self.min_new_tokens = (
torch.tensor(
data=[
req.sampling_params.min_new_tokens
for req in self.orchestrator.reqs()
],
dtype=torch.int32,
pin_memory=pin_memory,
)
.to(self.orchestrator.device, non_blocking=True)
.unsqueeze_(1)
)
padded_stop_token_ids = torch.nn.utils.rnn.pad_sequence(
padded_stop_token_ids_cpu = torch.nn.utils.rnn.pad_sequence(
sequences=[
torch.tensor(
data=[
@@ -40,13 +47,17 @@ class BatchedMinNewTokensPenalizer(_BatchedPenalizer):
if token_id is not None
],
dtype=torch.int64,
device=self.orchestrator.device,
)
for req in self.orchestrator.reqs()
],
batch_first=True,
padding_value=self.orchestrator.vocab_size,
)
if pin_memory:
padded_stop_token_ids_cpu = padded_stop_token_ids_cpu.pin_memory()
padded_stop_token_ids = padded_stop_token_ids_cpu.to(
self.orchestrator.device, non_blocking=True
)
self.stop_token_penalties = torch.zeros(
size=(len(self.orchestrator.reqs()), self.orchestrator.vocab_size + 1),
dtype=torch.float32,
@@ -1,6 +1,7 @@
import torch
from sglang.srt.sampling.penaltylib.orchestrator import _BatchedPenalizer
from sglang.srt.utils.common import is_pin_memory_available
class BatchedPresencePenalizer(_BatchedPenalizer):
@@ -15,6 +16,7 @@ class BatchedPresencePenalizer(_BatchedPenalizer):
)
def _prepare(self):
pin_memory = is_pin_memory_available(self.orchestrator.device)
self.cumulated_presence_penalties = torch.zeros(
(len(self.orchestrator.reqs()), self.orchestrator.vocab_size),
dtype=torch.float32,
@@ -28,9 +30,11 @@ class BatchedPresencePenalizer(_BatchedPenalizer):
for req in self.orchestrator.reqs()
],
dtype=torch.float32,
device=self.orchestrator.device,
pin_memory=pin_memory,
)
).unsqueeze_(1)
.to(self.orchestrator.device, non_blocking=True)
.unsqueeze_(1)
)
def _cumulate_output_tokens(self, output_ids: torch.Tensor):
self.cumulated_presence_penalties.scatter_(
@@ -2,6 +2,7 @@ import torch
from sglang.srt.sampling.penaltylib.orchestrator import _BatchedPenalizer
from sglang.srt.utils import get_compiler_backend, is_npu
from sglang.srt.utils.common import is_pin_memory_available
_is_npu = is_npu()
@@ -29,6 +30,7 @@ class BatchedRepetitionPenalizer(_BatchedPenalizer):
)
def _prepare(self):
pin_memory = is_pin_memory_available(self.orchestrator.device)
self.cumulated_repetition_penalties = torch.ones(
(len(self.orchestrator.reqs()), self.orchestrator.vocab_size),
dtype=torch.float32,
@@ -41,9 +43,11 @@ class BatchedRepetitionPenalizer(_BatchedPenalizer):
for req in self.orchestrator.reqs()
],
dtype=torch.float32,
device=self.orchestrator.device,
pin_memory=pin_memory,
)
).unsqueeze_(1)
.to(self.orchestrator.device, non_blocking=True)
.unsqueeze_(1)
)
def _cumulate_output_tokens(self, output_ids: torch.Tensor):
self.cumulated_repetition_penalties.scatter_(
@@ -158,10 +158,26 @@ class SamplingBatchInfo:
logit_bias = None
if any(r.sampling_params.logit_bias is not None for r in reqs):
logit_bias = torch.zeros(len(reqs), vocab_size, device=device)
rows, cols, vals = [], [], []
for i, r in enumerate(reqs):
if r.sampling_params.logit_bias is not None:
for key, value in r.sampling_params.logit_bias.items():
logit_bias[i, int(key)] = value
# Dedup on int(key) first ("1" and "01" collide): duplicate
# indices make the index_put below nondeterministic on CUDA.
row_bias = {
int(key): value
for key, value in r.sampling_params.logit_bias.items()
}
for token_id, value in row_bias.items():
rows.append(i)
cols.append(token_id)
vals.append(value)
if rows:
logit_bias[
_rows_to_device_indices(rows, device, _pin),
_rows_to_device_indices(cols, device, _pin),
] = torch.tensor(vals, dtype=logit_bias.dtype, pin_memory=_pin).to(
device, non_blocking=True
)
# Check if any request has custom logit processor
has_custom_logit_processor = (
@@ -0,0 +1,181 @@
"""Sampling metadata built on the host and copied to the device in one transfer."""
import unittest
from types import SimpleNamespace
from unittest.mock import patch
import torch
from torch.utils._python_dispatch import TorchDispatchMode
from sglang.srt.sampling.penaltylib import (
BatchedMinNewTokensPenalizer,
BatchedPenalizerOrchestrator,
)
from sglang.srt.sampling.sampling_batch_info import SamplingBatchInfo
from sglang.srt.sampling.sampling_params import SamplingParams
from sglang.test.ci.ci_register import register_cpu_ci, register_cuda_ci
from sglang.test.test_utils import CustomTestCase
register_cpu_ci(est_time=15, suite="base-a-test-cpu")
register_cuda_ci(est_time=20, stage="base-b-kernel-unit", runner_config="1-gpu-large")
VOCAB_SIZE = 32
class _Batch:
def __init__(self, reqs, device):
self.reqs = reqs
self.device = device
def _req(**sampling_params):
return SimpleNamespace(
sampling_params=SamplingParams(**sampling_params),
eos_token_ids=None,
tokenizer=SimpleNamespace(eos_token_id=None, additional_stop_token_ids=None),
custom_logit_processor=None,
return_sampling_mask=False,
)
class _H2DCopies(TorchDispatchMode):
"""Record the element count of every host-to-device copy."""
def __init__(self):
super().__init__()
self.numels = []
def __torch_dispatch__(self, func, types, args=(), kwargs=None):
kwargs = kwargs or {}
if func == torch.ops.aten._to_copy.default:
source = args[0]
target = kwargs.get("device")
if source.device.type == "cpu" and target and target.type == "cuda":
self.numels.append(source.numel())
return func(*args, **kwargs)
class _SamplingMetadataTestBase(CustomTestCase):
device = "cpu"
def setUp(self):
super().setUp()
exec_context = SimpleNamespace(
deterministic=SimpleNamespace(enable_deterministic_inference=False),
features=SimpleNamespace(enable_custom_logit_processor=True),
)
context_patch = patch(
"sglang.srt.sampling.sampling_batch_info.get_exec",
return_value=exec_context,
)
context_patch.start()
self.addCleanup(context_patch.stop)
def assert_device_tensor(self, actual, expected, dtype=None):
self.assertEqual(actual.device, torch.device(self.device))
if dtype is not None:
self.assertEqual(actual.dtype, dtype)
torch.testing.assert_close(actual.cpu(), expected, rtol=0, atol=0)
class TestSamplingMetadataCPU(_SamplingMetadataTestBase):
def test_min_tokens_pads_ragged_stop_sets(self):
reqs = [
_req(min_new_tokens=2, stop_token_ids=[3]),
_req(min_new_tokens=0, stop_token_ids=[5]),
_req(min_new_tokens=1),
]
# Row 0 unions four stop sources and must drop the None entries.
reqs[0].sampling_params.stop_token_ids.add(None)
reqs[0].eos_token_ids = {2}
reqs[0].tokenizer.additional_stop_token_ids = {4, None}
reqs[0].tokenizer.eos_token_id = 1
orch = BatchedPenalizerOrchestrator(
VOCAB_SIZE, _Batch(reqs, self.device), {BatchedMinNewTokensPenalizer}
)
self.assert_device_tensor(
orch.penalizers[BatchedMinNewTokensPenalizer].min_new_tokens,
torch.tensor([[2], [0], [1]], dtype=torch.int32),
torch.int32,
)
for step in range(3):
logits = torch.zeros(3, VOCAB_SIZE, device=self.device)
orch.apply(logits)
expected = torch.zeros(3, VOCAB_SIZE)
if step < 2:
expected[0, [1, 2, 3, 4]] = -torch.inf
self.assert_device_tensor(logits, expected)
orch.cumulate_output_tokens(
torch.ones(3, dtype=torch.long, device=self.device)
)
def test_min_tokens_without_any_stop_tokens(self):
orch = BatchedPenalizerOrchestrator(
VOCAB_SIZE,
_Batch([_req(min_new_tokens=1)], self.device),
{BatchedMinNewTokensPenalizer},
)
logits = torch.zeros(1, VOCAB_SIZE, device=self.device)
orch.apply(logits)
self.assert_device_tensor(logits, torch.zeros(1, VOCAB_SIZE))
def test_sparse_logit_bias_keeps_last_value_for_colliding_keys(self):
reqs = [
_req(logit_bias={"0": -100, "31": 100, "1": 2, "01": 3}),
_req(),
_req(logit_bias={}),
_req(logit_bias={"0": 0, "2": -1.25}),
]
info = SamplingBatchInfo.from_schedule_batch(
_Batch(reqs, self.device), VOCAB_SIZE
)
expected = torch.zeros(len(reqs), VOCAB_SIZE)
expected[0, 0], expected[0, 31], expected[0, 1] = -100, 100, 3
expected[3, 2] = -1.25
self.assert_device_tensor(info.logit_bias, expected, torch.float32)
def test_logit_bias_is_none_without_any_bias(self):
info = SamplingBatchInfo.from_schedule_batch(
_Batch([_req(), _req()], self.device), VOCAB_SIZE
)
self.assertIsNone(info.logit_bias)
@unittest.skipUnless(torch.cuda.is_available(), "requires CUDA")
class TestSamplingMetadataCUDA(_SamplingMetadataTestBase):
device = "cuda:0"
def test_stop_token_copy_count_does_not_grow_with_batch_size(self):
copy_counts = {}
for batch_size in (1, 16):
reqs = [
_req(min_new_tokens=2, stop_token_ids=[2, 3]) for _ in range(batch_size)
]
with _H2DCopies() as copies:
orch = BatchedPenalizerOrchestrator(
VOCAB_SIZE,
_Batch(reqs, self.device),
{BatchedMinNewTokensPenalizer},
)
logits = torch.zeros(batch_size, VOCAB_SIZE, device=self.device)
orch.apply(logits)
torch.cuda.synchronize()
copy_counts[batch_size] = len(copies.numels)
self.assertTrue(torch.isneginf(logits[:, 2:4]).all().item())
self.assertEqual(copy_counts[16], copy_counts[1])
def test_logit_bias_never_copies_a_dense_row(self):
reqs = [_req(logit_bias={"1": 2, "31": -1}), _req(), _req(logit_bias={})]
with _H2DCopies() as copies:
info = SamplingBatchInfo.from_schedule_batch(
_Batch(reqs, self.device), VOCAB_SIZE
)
torch.cuda.synchronize()
self.assertLess(max(copies.numels), VOCAB_SIZE)
expected = torch.zeros(len(reqs), VOCAB_SIZE)
expected[0, 1], expected[0, 31] = 2, -1
self.assert_device_tensor(info.logit_bias, expected, torch.float32)
if __name__ == "__main__":
unittest.main()