Add Python bindings for SYCL IPC memory via dpctl by zxue2 · Pull Request #2331 · IntelPython/dpctl

zxue2 · 2026-06-30T06:20:59Z

Add inter-process communication (IPC) support for SYCL USM memory, enabling zero-copy GPU memory sharing across processes. It wraps sycl::ext::oneapi::experimental::ipc::memory (get/open/close/put).

C API (libsyclinterface):

dpctl_sycl_ipc_memory_interface.h: declares DPCTLIPCMem_GetHandle, DPCTLIPCMem_OpenHandle, DPCTLIPCMem_CloseHandle, DPCTLIPCMem_FreeHandleData
dpctl_sycl_ipc_memory_interface.cpp: implements the C API by calling the SYCL experimental ipc::memory functions; auto-discovered by CMake.

Cython declarations:

_backend.pxd: extern block for the 4 new C functions

Python subpackage (dpctl.ipc):

IPCMemoryHandle: Cython extension class wrapping IPC memory export/import init(usm_memory): calls get() + put(), stores handle as bytes to_bytes(): serializable payload for cross-process transport open(handle_bytes, device, nbytes): returns MemoryUSMDevice close_mapping(usm_memory): explicitly closes an IPC mapping

Test In Docker (oneAPI 2026.0 installed):

python -c "
import dpctl
from dpctl.memory import MemoryUSMDevice
from dpctl.ipc import IPCMemoryHandle
d = dpctl.SyclDevice('level_zero:gpu')
q = dpctl.SyclQueue(d)
mem = MemoryUSMDevice(4096, queue=q)
h = IPCMemoryHandle(mem)
raw = h.to_bytes()
print(f'IPC handle: {len(raw)} bytes')
mem2 = IPCMemoryHandle.open(raw, d, nbytes=4096)
print(f'Opened: {mem2.nbytes} bytes on {mem2.sycl_device.name}')
IPCMemoryHandle.close_mapping(mem2)
print('close OK')
"

IPC handle: 120 bytes
Opened: 4096 bytes on Intel(R) Arc(TM) Pro B60 Graphics
close OK

Add inter-process communication (IPC) support for SYCL USM memory, enabling zero-copy GPU memory sharing across processes. It wraps sycl::ext::oneapi::experimental::ipc::memory (get/open/close/put). C API (libsyclinterface): - dpctl_sycl_ipc_memory_interface.h: declares DPCTLIPCMem_GetHandle, DPCTLIPCMem_OpenHandle, DPCTLIPCMem_CloseHandle, DPCTLIPCMem_FreeHandleData - dpctl_sycl_ipc_memory_interface.cpp: implements the C API by calling the SYCL experimental ipc::memory functions; auto-discovered by CMake. Cython declarations: - _backend.pxd: extern block for the 4 new C functions Python subpackage (dpctl.ipc): - IPCMemoryHandle: Cython extension class wrapping IPC memory export/import __init__(usm_memory): calls get() + put(), stores handle as bytes to_bytes(): serializable payload for cross-process transport open(handle_bytes, device, nbytes): returns MemoryUSMDevice close_mapping(usm_memory): explicitly closes an IPC mapping Signed-off-by: Zhan Xue <zhan.xue@intel.com>

ndgrigorian · 2026-06-30T18:47:41Z

+cdef class IPCMemoryHandle:
+    """Wrapper around a SYCL IPC memory handle.
+
+    Instances are created by passing a :class:`dpctl.memory.MemoryUSMDevice`


if this docstring is accurate and the extension only works with MemoryUSMDevice, then shouldn't we add isinstance check below to guarantee it's device memory?

Is it a requirement that it be a USM device allocation, or can host and/or shared work?

urIPCGetMemHandleExp without USM type restriction but urIPCOpenMemHandleExp is hardcoded to UR_USM_TYPE_DEVICE.
So urIPCOpenMemHandleExp may keep it safe. Please kindly double confirm it from UR.

btw, zeMemGetIpcHandle with device memory allocation and zeMemGetIpcHandleWithProperties with device or host memory allocation. I suppose there may be some extension in UR in future.

if this is the case, then let's add the check for isinstance(memory, USMDeviceMemory)

remove the class now

ndgrigorian · 2026-06-30T20:03:12Z

+        usm_memory._opaque_ptr = NULL
+        usm_memory._memory_ptr = NULL
+        usm_memory.nbytes = 0


this seems a bit dangerous for users

I think it would make the most sense to instead, since _opaque_ptr is std::shared_ptr, share the shared_ptr with the memory object shared pointer if possible

Could you pls make it as follow-up improvement with separate PR given there should be no obvious risk for current use case: deterministic ipc open/get/close, explicit-lifetime IPC resource?

I will instead open a PR into this branch which fixes this issue, I would prefer it be fixed before we merge anything

ndgrigorian · 2026-06-30T20:05:47Z

+# distutils: language = c++
+# cython: language_level=3
+
+"""Declarations for the IPCMemoryHandle Cython extension type."""


I'm conflicted on whether this belongs in a separate namespace or not. So far, we've been free with incorporating extensions into the main dpctl namespace, as long as we have fall-backs so that they don't crash, etc. when the extension is unavailable. This will enable us to use AdaptiveCpp in the future.

Having an entire submodule not be built is a bit different. Perhaps instead we can move this into dpctl.memory and implement fallbacks in the C-API and an is_available free function like we have for WorkGroupMemory, etc. to check for it

I would expect dpctl.ipc namespace to hold both memory ipc and event ipc . What about revisiting it post event ipc coming?

I understand it would hold both functionality, but I think it is still more sensible to incorporate it with existing modules as opposed to adding this new very specific submodule.

that is to say, if we move current IPC implementation into dpctl.memory and add fallbacks for if it isn't present, it would be fine as is

moved to dpctl.mem

add has_aspect_ext_oneapi_ipc_memory checks in __init__ and open() Signed-off-by: Zhan Xue <zhan.xue@intel.com>

coveralls · 2026-07-02T13:35:46Z

coverage: 75.411% (-0.3%) from 75.677% — zxue2:enable_ipc_mem into IntelPython:master

Migrate the SYCL IPC memory functionality from the standalone dpctl.ipc.IPCMemoryHandle class into methods on dpctl.memory._Memory: - _Memory.get_ipc_handle() - _Memory.open_ipc_handle() - _Memory.close_ipc_mapping() Signed-off-by: Zhan Xue <zhan.xue@intel.com>

zxue2 requested review from antonwolfy, ndgrigorian and vlad-perevezentsev as code owners June 30, 2026 06:21

ndgrigorian reviewed Jun 30, 2026

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Comment thread dpctl/ipc/_ipc_memory.pyx Outdated

ndgrigorian reviewed Jun 30, 2026

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Comment thread dpctl/ipc/_ipc_memory.pyx Outdated

ndgrigorian reviewed Jun 30, 2026

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zxue2 force-pushed the enable_ipc_mem branch from 352d2f8 to 3dea379 Compare July 1, 2026 13:12

Add aspect::ext_oneapi_ipc_memory for SyclDevice

3dea379

add has_aspect_ext_oneapi_ipc_memory checks in __init__ and open() Signed-off-by: Zhan Xue <zhan.xue@intel.com>

zxue2 force-pushed the enable_ipc_mem branch from 83bb9b4 to b2c490f Compare July 2, 2026 13:22

zxue2 force-pushed the enable_ipc_mem branch 2 times, most recently from 076d34f to 89ec05e Compare July 2, 2026 14:03

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zxue2 commented Jun 30, 2026

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coveralls commented Jul 2, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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coveralls commented Jul 2, 2026 •

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