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CANN: Fix ggml_cann_set_device to avoid redundant device switches #15935

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Merged
merged 2 commits into from
Sep 17, 2025
+10 −7
Merged

CANN: Fix ggml_cann_set_device to avoid redundant device switches #15935

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86b6852
CANN: Fix ggml_cann_set_device to avoid redundant device switches
noemotiovon Sep 11, 2025
c37e94b
CANN: add device default id
noemotiovon Sep 15, 2025
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5 changes: 4 additions & 1 deletion ggml/src/ggml-cann/common.h
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Original file line number Diff line number Diff line change
Expand Up @@ -526,7 +526,10 @@ struct ggml_backend_cann_context {
*/
aclrtStream stream(int stream) {
if (streams[stream] == nullptr) {
ggml_cann_set_device(device);
// If the device is not set here, destroying the stream later may cause a mismatch
// between the thread contexts where the stream was created and destroyed.
// However, I printed the device_id, thread_id, and stream, and they are all consistent.
ACL_CHECK(aclrtSetDevice(device));
ACL_CHECK(aclrtCreateStream(&streams[stream]));
}
return streams[stream];
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12 changes: 6 additions & 6 deletions ggml/src/ggml-cann/ggml-cann.cpp
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Expand Up @@ -75,13 +75,12 @@
* @param device The device ID to set.
*/
void ggml_cann_set_device(const int32_t device) {
// TODO: uncomment these lines after empty context has fixed.
// int current_device;
// ACL_CHECK(aclrtGetDevice(&current_device));
int current_device = -1;
aclrtGetDevice(&current_device);

// if (device == current_device) {
// return;
// }
if (device == current_device) {
return;
}
ACL_CHECK(aclrtSetDevice(device));
}

Expand Down Expand Up @@ -1729,6 +1728,7 @@ static bool ggml_cann_compute_forward(ggml_backend_cann_context& ctx,
ggml_cann_get_rows(ctx, dst);
break;
case GGML_OP_SET_ROWS:
std::cout << "lcg GGML_OP_SET_ROWS"<< std::endl;
ggml_cann_set_rows(ctx, dst);
break;
case GGML_OP_DUP:
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