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16 changes: 10 additions & 6 deletions src/diffusers/schedulers/scheduling_cosine_dpmsolver_multistep.py
Original file line number Diff line number Diff line change
Expand Up @@ -280,15 +280,15 @@ def set_timesteps(self, num_inference_steps: int | None = None, device: str | to
self.timesteps = self.precondition_noise(sigmas)

if self.config.final_sigmas_type == "sigma_min":
sigma_last = self.config.sigma_min
sigma_last = sigmas[-1:]
elif self.config.final_sigmas_type == "zero":
sigma_last = 0
sigma_last = torch.zeros(1, dtype=torch.float32, device=device)
else:
raise ValueError(
f"`final_sigmas_type` must be one of 'zero', or 'sigma_min', but got {self.config.final_sigmas_type}"
)

self.sigmas = torch.cat([sigmas, torch.tensor([sigma_last], dtype=torch.float32, device=device)])
self.sigmas = torch.cat([sigmas, sigma_last])

self.model_outputs = [
None,
Expand Down Expand Up @@ -643,6 +643,7 @@ def step(
self.config.euler_at_final
or (self.config.lower_order_final and len(self.timesteps) < 15)
or self.config.final_sigmas_type == "zero"
or bool(self.sigmas[self.step_index + 1] == self.sigmas[self.step_index])
)
lower_order_second = (
(self.step_index == len(self.timesteps) - 2) and self.config.lower_order_final and len(self.timesteps) < 15
Expand All @@ -665,9 +666,12 @@ def step(
sigma_max=self.config.sigma_max,
seed=seed,
)
noise = self.noise_sampler(self.sigmas[self.step_index], self.sigmas[self.step_index + 1]).to(
model_output.device
)
if self.sigmas[self.step_index + 1] == self.sigmas[self.step_index]:
noise = torch.zeros_like(model_output)
else:
noise = self.noise_sampler(self.sigmas[self.step_index], self.sigmas[self.step_index + 1]).to(
model_output.device
)

if self.config.solver_order == 1 or self.lower_order_nums < 1 or lower_order_final:
prev_sample = self.dpm_solver_first_order_update(model_output, sample=sample, noise=noise)
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -1058,7 +1058,9 @@ def step(

# Improve numerical stability for small number of steps
lower_order_final = (self.step_index == len(self.timesteps) - 1) and (
self.config.euler_at_final or (self.config.lower_order_final and len(self.timesteps) < 15)
self.config.euler_at_final
or (self.config.lower_order_final and len(self.timesteps) < 15)
or bool(self.sigmas[self.step_index + 1] == self.sigmas[self.step_index])
)
lower_order_second = (
(self.step_index == len(self.timesteps) - 2) and self.config.lower_order_final and len(self.timesteps) < 15
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -303,15 +303,15 @@ def set_timesteps(
self.timesteps = self.precondition_noise(sigmas)

if self.config.final_sigmas_type == "sigma_min":
sigma_last = self.config.sigma_min
sigma_last = sigmas[-1:]
elif self.config.final_sigmas_type == "zero":
sigma_last = 0
sigma_last = torch.zeros(1, dtype=torch.float32, device=device)
else:
raise ValueError(
f"`final_sigmas_type` must be one of 'zero', or 'sigma_min', but got {self.config.final_sigmas_type}"
)

self.sigmas = torch.cat([sigmas, torch.tensor([sigma_last], dtype=torch.float32, device=device)])
self.sigmas = torch.cat([sigmas, sigma_last])

self.model_outputs = [
None,
Expand Down Expand Up @@ -766,6 +766,7 @@ def step(
self.config.euler_at_final
or (self.config.lower_order_final and len(self.timesteps) < 15)
or self.config.final_sigmas_type == "zero"
or bool(self.sigmas[self.step_index + 1] == self.sigmas[self.step_index])
)
lower_order_second = (
(self.step_index == len(self.timesteps) - 2) and self.config.lower_order_final and len(self.timesteps) < 15
Expand Down
20 changes: 20 additions & 0 deletions tests/schedulers/test_scheduler_dpm_multi_inverse.py
Original file line number Diff line number Diff line change
Expand Up @@ -271,3 +271,23 @@ def test_beta_sigmas(self):

def test_exponential_sigmas(self):
self.check_over_configs(use_exponential_sigmas=True)

def test_zero_width_final_step(self):
scheduler_class = self.scheduler_classes[0]
model = self.dummy_model()
for kwargs in [
{"solver_order": 3, "use_karras_sigmas": True},
{"solver_order": 3, "use_exponential_sigmas": True},
{"solver_order": 3, "use_beta_sigmas": True},
{"solver_order": 3, "timestep_spacing": "trailing"},
{"solver_order": 2, "solver_type": "heun", "use_karras_sigmas": True},
]:
scheduler_config = self.get_scheduler_config(**kwargs)
scheduler = scheduler_class(**scheduler_config)
scheduler.set_timesteps(20)
sample = self.dummy_sample_deter
generator = torch.manual_seed(0)
for t in scheduler.timesteps:
residual = model(sample, t)
sample = scheduler.step(residual, t, sample, generator=generator).prev_sample
assert not torch.isnan(sample).any()
53 changes: 51 additions & 2 deletions tests/schedulers/test_scheduler_edm_dpmsolver_multistep.py
Original file line number Diff line number Diff line change
Expand Up @@ -165,8 +165,6 @@ def test_prediction_type(self):
for prediction_type in ["epsilon", "v_prediction"]:
self.check_over_configs(prediction_type=prediction_type)

# TODO (patil-suraj): Fix this test
@unittest.skip("Skip for now, as it failing currently but works with the actual model")
def test_solver_order_and_type(self):
for algorithm_type in ["dpmsolver++", "sde-dpmsolver++"]:
for solver_type in ["midpoint", "heun"]:
Expand Down Expand Up @@ -260,3 +258,54 @@ def test_duplicated_timesteps(self, **config):
@unittest.skip("Test not supported.")
def test_trained_betas(self):
pass

def test_zero_width_final_step(self):
scheduler_class = self.scheduler_classes[0]
model = self.dummy_model()
for kwargs in [
{"solver_order": 3, "sigma_schedule": "karras", "final_sigmas_type": "sigma_min"},
{"solver_order": 3, "sigma_schedule": "exponential", "final_sigmas_type": "sigma_min"},
{"solver_order": 2, "solver_type": "heun", "sigma_schedule": "karras", "final_sigmas_type": "sigma_min"},
{
"solver_order": 2,
"solver_type": "heun",
"algorithm_type": "sde-dpmsolver++",
"sigma_min": 0.01,
"final_sigmas_type": "sigma_min",
},
{
"solver_order": 1,
"algorithm_type": "sde-dpmsolver++",
"sigma_min": 0.01,
"final_sigmas_type": "sigma_min",
},
]:
scheduler_config = self.get_scheduler_config(**kwargs)
scheduler = scheduler_class(**scheduler_config)
scheduler.set_timesteps(20)
sample = self.dummy_sample_deter
generator = torch.manual_seed(0)
for t in scheduler.timesteps:
residual = model(sample, t)
sample = scheduler.step(residual, t, sample, generator=generator).prev_sample
assert not torch.isnan(sample).any()

from diffusers import CosineDPMSolverMultistepScheduler

for solver_order in [1, 2]:
for solver_type in ["midpoint", "heun"]:
cosine_scheduler = CosineDPMSolverMultistepScheduler(
solver_order=solver_order,
solver_type=solver_type,
final_sigmas_type="sigma_min",
)
cosine_scheduler.set_timesteps(10)
sample = self.dummy_sample_deter
# BrownianTreeNoiseSampler divides by sqrt(|t1 - t0|) and yields NaN when sigma == sigma_next
cosine_scheduler.noise_sampler = lambda s, s_next: (
torch.full_like(sample, float("nan")) if s == s_next else torch.zeros_like(sample)
)
for t in cosine_scheduler.timesteps:
residual = model(sample, t)
sample = cosine_scheduler.step(residual, t, sample).prev_sample
assert not torch.isnan(sample).any()
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