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Minor updates to OffloadPC #5164

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Minor updates to OffloadPC #5164

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f3b58a6
Minor updates to OffloadPC
dsroberts Jun 11, 2026
79447e9
Add check for silent P matrix conversion
dsroberts Jun 11, 2026
4ab1ef4
Update firedrake/preconditioners/offload.py
dsroberts Jun 11, 2026
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15 changes: 12 additions & 3 deletions firedrake/preconditioners/offload.py
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,8 @@
}
}

_no_offload_mat_types = ("python", "schurcompliment")
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class OffloadPC(PCBase):
"""Offload PC from CPU to GPU and back.
Expand Down Expand Up @@ -53,8 +55,15 @@ def initialize(self, pc):
pc.setOptionsPrefix(options_prefix)
if self.device_mat is not None:
with PETSc.Log.Event("Event: initialize offload"):
P_dev = P.convert(mat_type=self.device_mat)
A_dev = P_dev if A.handle == P.handle else A.convert(mat_type=self.device_mat)
P_dev = PETSc.Mat()
P_dev = P.convert(mat_type=self.device_mat, out=P_dev)
if A.handle == P.handle:
A_dev = P_dev
elif A.getType() in _no_offload_mat_types:
A_dev = A
else:
A_dev = PETSc.Mat()
A_dev = A.convert(mat_type=self.device_mat, out=A_dev)
P_dev.setNullSpace(P.getNullSpace())
P_dev.setTransposeNullSpace(P.getTransposeNullSpace())
P_dev.setNearNullSpace(P.getNearNullSpace())
Expand All @@ -74,7 +83,7 @@ def update(self, pc):
A, P = pc.getOperators()
A_dev, P_dev = self.pc.getOperators()
P.copy(P_dev)
if A_dev.handle != P_dev.handle:
if A_dev.handle != P_dev.handle and A.getType() not in _no_offload_mat_types:
A.copy(A_dev)

# Convert vectors to CUDA, solve and get solution on CPU back
Expand Down
3 changes: 3 additions & 0 deletions tests/firedrake/offload/test_poisson_offloading_pc.py
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Expand Up @@ -55,6 +55,9 @@ def run_test_poisson_offload(ksp_type, pc_type, homogeneous_bcs):
problem = LinearVariationalProblem(L, R, u_f, bcs=bcs)
solver = LinearVariationalSolver(problem, solver_parameters=parameters)
solver.solve()

assert solver.snes.ksp.pc.getOperators()[1].getType() == "seqaij"

return errornorm(u_f, sol)


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