diff --git a/doc/python/hardware.rst b/doc/python/hardware.rst
index f1eb88fc7f4368a74c2b74f15aa4295871b4ccac..33c403ba10301eea6089e630de5287924e0da87e 100644
--- a/doc/python/hardware.rst
+++ b/doc/python/hardware.rst
@@ -8,6 +8,9 @@ Arbor provides two ways for working with hardware resources:
* *Prescribe* the hardware resources and their contexts for use in Arbor simulations.
* *Query* available hardware resources (e.g. the number of available GPUs), and initializing MPI.
+Note that to utilize some hardware features Arbor must be built and installed with the feature enabled, for example MPI or a GPU.
+Please refer to the :ref:`installation guide <in_build_install>` for information on how to enable hardware support.
+
Available resources
-------------------
@@ -127,10 +130,6 @@ The Python wrapper provides an API for:
provided by :class:`context`, instead they configure contexts, which are passed to
Arbor interfaces for domain decomposition and simulation.
- .. function:: context()
-
- Construct a local context with one thread, no GPU, no MPI.
-
.. function:: context(threads, gpu_id, mpi)
:noindex:
@@ -144,20 +143,13 @@ The Python wrapper provides an API for:
The identifier of the GPU to use, ``None`` by default.
Must be ``None``, or a non-negative integer.
+ Can only be set when Arbor was built with GPU support.
.. attribute:: mpi
- The MPI communicator (see :class:`mpi_comm`).
- mpi must be ``None``, or an MPI communicator.
-
- .. function:: context(alloc)
- :noindex:
-
- Create a local context, with no distributed/MPI, that uses the local resources described by :class:`proc_allocation`.
-
- .. attribute:: alloc
-
- The computational resources, one thread and no GPU by default.
+ The MPI communicator (see :class:`mpi_comm`), ``None`` by default.
+ Must be ``None``, or an MPI communicator.
+ Can only be set when Arbor was built with MPI support.
.. function:: context(alloc, mpi)
:noindex:
@@ -171,22 +163,9 @@ The Python wrapper provides an API for:
.. attribute:: mpi
- The MPI communicator (see :class:`mpi_comm`).
+ The MPI communicator (see :class:`mpi_comm`). ``None`` by default.
mpi must be ``None``, or an MPI communicator.
-
- .. function:: context(threads, gpu_id)
- :noindex:
-
- Create a context that uses a set number of :attr:`threads` and the GPU with id :attr:`gpu_id`.
-
- .. attribute:: threads
-
- The number of threads available locally for execution, 1 by default.
-
- .. attribute:: gpu_id
-
- The identifier of the GPU to use, ``None`` by default.
- Must be ``None``, or a non-negative integer.
+ Can only be set when Arbor was built with MPI support.
Contexts can be queried for information about which features a context has enabled,
whether it has a GPU, how many threads are in its thread pool.
diff --git a/python/context.cpp b/python/context.cpp
index e8cd4dbcb61a0cd5365f5d69c2c1f45f13ce234b..4bf1e462239621d2b65f2dfaec8f636f94209de4 100644
--- a/python/context.cpp
+++ b/python/context.cpp
@@ -93,66 +93,67 @@ void register_contexts(pybind11::module& m) {
// context
pybind11::class_<context_shim> context(m, "context", "An opaque handle for the hardware resources used in a simulation.");
context
- .def(pybind11::init<>(
- [](){return context_shim(arb::make_context());}),
- "Construct a local context with one thread, no GPU, no MPI by default.\n"
- )
- .def(pybind11::init(
- [](const proc_allocation_shim& alloc){
- return context_shim(arb::make_context(alloc.allocation())); }),
- "alloc"_a,
- "Construct a local context with argument:\n"
- " alloc: The computational resources to be used for the simulation.\n")
-#ifdef ARB_MPI_ENABLED
- .def(pybind11::init(
- [](proc_allocation_shim alloc, pybind11::object mpi){
- const char* mpi_err_str = "mpi must be None, or an MPI communicator";
- auto a = alloc.allocation(); // unwrap the C++ resource_allocation description
- if (can_convert_to_mpi_comm(mpi)) {
- return context_shim(arb::make_context(a, convert_to_mpi_comm(mpi)));
- }
- if (auto c = py2optional<mpi_comm_shim>(mpi, mpi_err_str)) {
- return context_shim(arb::make_context(a, c->comm));
- }
- return context_shim(arb::make_context(a));
- }),
- "alloc"_a, "mpi"_a=pybind11::none(),
- "Construct a distributed context with arguments:\n"
- " alloc: The computational resources to be used for the simulation.\n"
- " mpi: The MPI communicator, None by default.\n")
.def(pybind11::init(
[](int threads, pybind11::object gpu, pybind11::object mpi){
const char* gpu_err_str = "gpu_id must be None, or a non-negative integer";
- const char* mpi_err_str = "mpi must be None, or an MPI communicator";
+
+#ifndef ARB_GPU_ENABLED
+ if (!gpu.is_none()) {
+ throw pyarb_error("Attempt to set an GPU communicator but Arbor is not configured with GPU support.");
+ }
+#endif
auto gpu_id = py2optional<int>(gpu, gpu_err_str, is_nonneg());
arb::proc_allocation alloc(threads, gpu_id.value_or(-1));
+#ifndef ARB_MPI_ENABLED
+ if (!mpi.is_none()) {
+ throw pyarb_error("Attempt to set an MPI communicator but Arbor is not configured with MPI support.");
+ }
+#else
+ const char* mpi_err_str = "mpi must be None, or an MPI communicator";
if (can_convert_to_mpi_comm(mpi)) {
return context_shim(arb::make_context(alloc, convert_to_mpi_comm(mpi)));
}
if (auto c = py2optional<mpi_comm_shim>(mpi, mpi_err_str)) {
return context_shim(arb::make_context(alloc, c->comm));
}
+#endif
return context_shim(arb::make_context(alloc));
}),
"threads"_a=1, "gpu_id"_a=pybind11::none(), "mpi"_a=pybind11::none(),
"Construct a distributed context with arguments:\n"
" threads: The number of threads available locally for execution, 1 by default.\n"
- " gpu_id: The identifier of the GPU to use, None by default.\n"
- " mpi: The MPI communicator, None by default.\n")
-#else
+ " gpu_id: The identifier of the GPU to use, None by default. Only available if arbor.__config__['gpu']==True.\n"
+ " mpi: The MPI communicator, None by default. Only available if arbor.__config__['mpi']==True.\n")
.def(pybind11::init(
- [](int threads, pybind11::object gpu){
- auto gpu_id = py2optional<int>(gpu, "gpu_id must be None, or a non-negative integer", is_nonneg());
- return context_shim(arb::make_context(arb::proc_allocation(threads, gpu_id.value_or(-1))));
- }),
- "threads"_a=1, "gpu_id"_a=pybind11::none(),
- "Construct a local context with arguments:\n"
- " threads: The number of threads available locally for execution, 1 by default.\n"
- " gpu_id: The identifier of the GPU to use, None by default.\n")
+ [](proc_allocation_shim alloc, pybind11::object mpi){
+ auto a = alloc.allocation(); // unwrap the C++ resource_allocation description
+#ifndef ARB_GPU_ENABLED
+ if (a.has_gpu()) {
+ throw pyarb_error("Attempt to set an GPU communicator but Arbor is not configured with GPU support.");
+ }
+#endif
+#ifndef ARB_MPI_ENABLED
+ if (!mpi.is_none()) {
+ throw pyarb_error("Attempt to set an MPI communicator but Arbor is not configured with MPI support.");
+ }
+#else
+ const char* mpi_err_str = "mpi must be None, or an MPI communicator";
+ if (can_convert_to_mpi_comm(mpi)) {
+ return context_shim(arb::make_context(a, convert_to_mpi_comm(mpi)));
+ }
+ if (auto c = py2optional<mpi_comm_shim>(mpi, mpi_err_str)) {
+ return context_shim(arb::make_context(a, c->comm));
+ }
#endif
+ return context_shim(arb::make_context(a));
+ }),
+ "alloc"_a, "mpi"_a=pybind11::none(),
+ "Construct a distributed context with arguments:\n"
+ " alloc: The computational resources to be used for the simulation.\n"
+ " mpi: The MPI communicator, None by default. Only available if arbor.__config__['mpi']==True.\n")
.def_property_readonly("has_mpi", [](const context_shim& ctx){return arb::has_mpi(ctx.context);},
"Whether the context uses MPI for distributed communication.")
.def_property_readonly("has_gpu", [](const context_shim& ctx){return arb::has_gpu(ctx.context);},
diff --git a/python/mpi.cpp b/python/mpi.cpp
index d3de709f86c1116d7fb41300be4a744b625f75e0..1661a42dcf811af0a6c96db142b9d611303813d0 100644
--- a/python/mpi.cpp
+++ b/python/mpi.cpp
@@ -34,7 +34,7 @@ MPI_Comm convert_to_mpi_comm(pybind11::object o) {
return *PyMPIComm_Get(o.ptr());
}
#endif
- throw arb::mpi_error(MPI_ERR_OTHER, "Unable to convert to an MPI Communicatior");
+ throw arb::mpi_error(MPI_ERR_OTHER, "Invalid MPI Communicatior");
}
mpi_comm_shim::mpi_comm_shim(pybind11::object o) {