From be55695eff44784a141a863f273661a6bce63dfc Mon Sep 17 00:00:00 2001 From: slaren Date: Wed, 7 Aug 2024 13:29:02 +0200 Subject: [PATCH] ggml-backend : fix async copy from CPU (#8897) * ggml-backend : fix async copy from CPU * cuda : more reliable async copy, fix stream used when the devices are the same --- ggml/src/ggml-backend.c | 25 +++++++++++++++---------- ggml/src/ggml-cuda.cu | 28 +++++++++++++++------------- 2 files changed, 30 insertions(+), 23 deletions(-) diff --git a/ggml/src/ggml-backend.c b/ggml/src/ggml-backend.c index 954ab20725acc..e1651cc645c42 100644 --- a/ggml/src/ggml-backend.c +++ b/ggml/src/ggml-backend.c @@ -351,15 +351,10 @@ void ggml_backend_tensor_copy_async(ggml_backend_t backend_src, ggml_backend_t b } // an async copy would normally happen after all the queued operations on both backends are completed - // sync src, set_async dst - if (ggml_backend_buffer_is_host(src->buffer)) { - ggml_backend_synchronize(backend_src); - ggml_backend_tensor_set_async(backend_dst, dst, src->data, 0, ggml_nbytes(src)); - } else { - ggml_backend_synchronize(backend_src); - ggml_backend_tensor_copy(src, dst); - ggml_backend_synchronize(backend_dst); - } + // to simulate the same behavior, we need to synchronize both backends first, and do a blocking copy + ggml_backend_synchronize(backend_src); + ggml_backend_synchronize(backend_dst); + ggml_backend_tensor_copy(src, dst); } // events @@ -1782,7 +1777,17 @@ static enum ggml_status ggml_backend_sched_compute_splits(ggml_backend_sched_t s } else { ggml_backend_synchronize(split_backend); } - ggml_backend_tensor_copy_async(input_backend, split_backend, input, input_cpy); + // try async copy, but if not possible, we can still use a sync copy without synchronizing the dst backend, since we handle the synchronization here with multiple copies and events + // TODO: add public function to facilitate this, since applications do not have direct access to the backend interface + if (!split_backend->iface.cpy_tensor_async || !split_backend->iface.cpy_tensor_async(input_backend, split_backend, input, input_cpy)) { + ggml_backend_synchronize(input_backend); + if (sched->events[split_backend_id][sched->cur_copy] != NULL) { + ggml_backend_event_synchronize(sched->events[split_backend_id][sched->cur_copy]); + } else { + ggml_backend_synchronize(split_backend); + } + ggml_backend_tensor_copy(input, input_cpy); + } } } diff --git a/ggml/src/ggml-cuda.cu b/ggml/src/ggml-cuda.cu index a00a7af6ca8b1..682c30d45bcf4 100644 --- a/ggml/src/ggml-cuda.cu +++ b/ggml/src/ggml-cuda.cu @@ -2358,33 +2358,35 @@ GGML_CALL static void ggml_backend_cuda_get_tensor_async(ggml_backend_t backend, } GGML_CALL static bool ggml_backend_cuda_cpy_tensor_async(ggml_backend_t backend_src, ggml_backend_t backend_dst, const ggml_tensor * src, ggml_tensor * dst) { - GGML_ASSERT(ggml_backend_is_cuda(backend_src) || ggml_backend_is_cuda(backend_dst)); - ggml_backend_buffer_t buf_src = src->view_src ? src->view_src->buffer : src->buffer; ggml_backend_buffer_t buf_dst = dst->view_src ? dst->view_src->buffer : dst->buffer; - if (!ggml_backend_buffer_is_cuda(src->buffer)) { + if (!ggml_backend_is_cuda(backend_src) || !ggml_backend_is_cuda(backend_dst)) { return false; } - if (!ggml_backend_buffer_is_cuda(dst->buffer)) { + if (!ggml_backend_buffer_is_cuda(src->buffer) || !ggml_backend_buffer_is_cuda(dst->buffer)) { return false; } - // device -> device + // device -> device copy ggml_backend_cuda_context * cuda_ctx_src = (ggml_backend_cuda_context *)backend_src->context; ggml_backend_cuda_context * cuda_ctx_dst = (ggml_backend_cuda_context *)backend_dst->context; - if (backend_src != backend_dst) { - ggml_backend_cuda_buffer_context * buf_ctx_src = (ggml_backend_cuda_buffer_context *)buf_src->context; - ggml_backend_cuda_buffer_context * buf_ctx_dst = (ggml_backend_cuda_buffer_context *)buf_dst->context; + ggml_backend_cuda_buffer_context * buf_ctx_src = (ggml_backend_cuda_buffer_context *)buf_src->context; + ggml_backend_cuda_buffer_context * buf_ctx_dst = (ggml_backend_cuda_buffer_context *)buf_dst->context; - GGML_ASSERT(cuda_ctx_src->device == buf_ctx_src->device); - GGML_ASSERT(cuda_ctx_dst->device == buf_ctx_dst->device); + if (cuda_ctx_src->device != buf_ctx_src->device || cuda_ctx_dst->device != buf_ctx_dst->device) { +#ifndef NDEBUG + GGML_CUDA_LOG_WARN("%s: backend and buffer devices do not match\n", __func__); +#endif + return false; + } + if (backend_src != backend_dst) { // copy on src stream if (cuda_ctx_src->device == cuda_ctx_dst->device) { - CUDA_CHECK(cudaMemcpyAsync(dst->data, src->data, ggml_nbytes(dst), cudaMemcpyDeviceToDevice, cuda_ctx_dst->stream())); + CUDA_CHECK(cudaMemcpyAsync(dst->data, src->data, ggml_nbytes(dst), cudaMemcpyDeviceToDevice, cuda_ctx_src->stream())); } else { #ifdef GGML_CUDA_NO_PEER_COPY return false; @@ -2393,7 +2395,7 @@ GGML_CALL static bool ggml_backend_cuda_cpy_tensor_async(ggml_backend_t backend_ #endif } - // record event on src stream + // record event on src stream after the copy if (!cuda_ctx_src->copy_event) { ggml_cuda_set_device(cuda_ctx_src->device); CUDA_CHECK(cudaEventCreateWithFlags(&cuda_ctx_src->copy_event, cudaEventDisableTiming)); @@ -2405,7 +2407,7 @@ GGML_CALL static bool ggml_backend_cuda_cpy_tensor_async(ggml_backend_t backend_ CUDA_CHECK(cudaStreamWaitEvent(cuda_ctx_dst->stream(), cuda_ctx_src->copy_event, 0)); } else { // src and dst are on the same backend - CUDA_CHECK(cudaMemcpyAsync(dst->data, src->data, ggml_nbytes(dst), cudaMemcpyDeviceToDevice, cuda_ctx_dst->stream())); + CUDA_CHECK(cudaMemcpyAsync(dst->data, src->data, ggml_nbytes(dst), cudaMemcpyDeviceToDevice, cuda_ctx_src->stream())); } return true; }