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CANN: Switch to stream synchronization #15809

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Merged
merged 2 commits into from
Sep 8, 2025
Merged

CANN: Switch to stream synchronization #15809

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CANN: Switch to stream synchronization
noemotiovon Sep 5, 2025
cff658d
CANN: add Comments
noemotiovon Sep 5, 2025
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19 changes: 10 additions & 9 deletions ggml/src/ggml-cann/ggml-cann.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2092,16 +2092,17 @@ static bool ggml_backend_cann_cpy_tensor_async(
ACL_CHECK(aclrtMemcpyAsync(dst->data, copy_size, src->data, copy_size,
ACL_MEMCPY_DEVICE_TO_DEVICE,
cann_ctx_src->stream()));

// record event on src stream after the copy
if (!cann_ctx_src->copy_event) {
ACL_CHECK(aclrtCreateEventWithFlag(&cann_ctx_src->copy_event, ACL_EVENT_SYNC));
}
ACL_CHECK(aclrtRecordEvent(cann_ctx_src->copy_event, cann_ctx_src->stream()));

// wait on dst stream for the copy to complete
ggml_cann_set_device(cann_ctx_dst->device);
ACL_CHECK(aclrtStreamWaitEvent(cann_ctx_dst->stream(), cann_ctx_src->copy_event));
// TODO: this event is not effective with acl graph mode, change to use aclrtSynchronizeStream
// if (!cann_ctx_src->copy_event) {
// ACL_CHECK(aclrtCreateEventWithFlag(&cann_ctx_src->copy_event, ACL_EVENT_SYNC));
// }
// ACL_CHECK(aclrtRecordEvent(cann_ctx_src->copy_event, cann_ctx_src->stream()));

// // wait on dst stream for the copy to complete
// ggml_cann_set_device(cann_ctx_dst->device);
// ACL_CHECK(aclrtStreamWaitEvent(cann_ctx_dst->stream(), cann_ctx_src->copy_event));
ACL_CHECK(aclrtSynchronizeStream(cann_ctx_src->stream()));
} else {
// src and dst are on the same backend
ACL_CHECK(aclrtMemcpyAsync(dst->data, copy_size, src->data, copy_size,
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