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| author | Tobias Burnus <tburnus@baylibre.com> | 2024-05-29 15:14:38 +0200 |
|---|---|---|
| committer | Tobias Burnus <tburnus@baylibre.com> | 2024-05-29 15:14:38 +0200 |
| commit | 4ccb3366ade6ec9493f8ca20ab73b0da4b9816db (patch) | |
| tree | a4f4a29116032e83903cb2352021873e7f5bfb2a /libgomp/plugin | |
| parent | 19c491d1848a8410559247183597096778967edf (diff) | |
libgomp: Enable USM for some nvptx devices
A few high-end nvptx devices support the attribute
CU_DEVICE_ATTRIBUTE_PAGEABLE_MEMORY_ACCESS; for those, unified shared
memory is supported in hardware. This patch enables support for those -
if all installed nvptx devices have this feature (as the capabilities
are per device type).
This exposes a bug in gomp_copy_back_icvs as it did before use
omp_get_mapped_ptr to find mapped variables, but that returns
the unchanged pointer in cased of shared memory. But in this case,
we have a few actually mapped pointers - like the ICV variables.
Additionally, there was a mismatch with regards to '-1' for the
device number as gomp_copy_back_icvs and omp_get_mapped_ptr count
differently. Hence, do the lookup manually.
include/ChangeLog:
* cuda/cuda.h (CU_DEVICE_ATTRIBUTE_PAGEABLE_MEMORY_ACCESS): Add.
libgomp/ChangeLog:
* libgomp.texi (nvptx): Update USM description.
* plugin/plugin-nvptx.c (GOMP_OFFLOAD_get_num_devices):
Claim support when requesting USM and all devices support
CU_DEVICE_ATTRIBUTE_PAGEABLE_MEMORY_ACCESS.
* target.c (gomp_copy_back_icvs): Fix device ptr lookup.
(gomp_target_init): Set GOMP_OFFLOAD_CAP_SHARED_MEM is the
devices supports USM.
Diffstat (limited to 'libgomp/plugin')
| -rw-r--r-- | libgomp/plugin/plugin-nvptx.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/libgomp/plugin/plugin-nvptx.c b/libgomp/plugin/plugin-nvptx.c index 5aad3448a8d..4cedc5390a3 100644 --- a/libgomp/plugin/plugin-nvptx.c +++ b/libgomp/plugin/plugin-nvptx.c @@ -1201,8 +1201,23 @@ GOMP_OFFLOAD_get_num_devices (unsigned int omp_requires_mask) if (num_devices > 0 && ((omp_requires_mask & ~(GOMP_REQUIRES_UNIFIED_ADDRESS + | GOMP_REQUIRES_UNIFIED_SHARED_MEMORY | GOMP_REQUIRES_REVERSE_OFFLOAD)) != 0)) return -1; + /* Check whether host page access (direct or via migration) is supported; + if so, enable USM. Currently, capabilities is per device type, hence, + check all devices. */ + if (num_devices > 0 + && (omp_requires_mask & GOMP_REQUIRES_UNIFIED_SHARED_MEMORY)) + for (int dev = 0; dev < num_devices; dev++) + { + int pi; + CUresult r; + r = CUDA_CALL_NOCHECK (cuDeviceGetAttribute, &pi, + CU_DEVICE_ATTRIBUTE_PAGEABLE_MEMORY_ACCESS, dev); + if (r != CUDA_SUCCESS || pi == 0) + return -1; + } return num_devices; } |