From 02325685ae5fcfc0aebd02a89ccb4b38dcd68d5d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johannes=20G=C3=A4=C3=9Fler?= <johannesg@5d6.de>
Date: Sat, 7 Feb 2026 23:34:01 +0100
Subject: [PATCH] unconditional peer access

---
 ggml/src/ggml-cuda/ggml-cuda.cu | 76 ++++++---------------------------
 1 file changed, 13 insertions(+), 63 deletions(-)

diff --git a/ggml/src/ggml-cuda/ggml-cuda.cu b/ggml/src/ggml-cuda/ggml-cuda.cu
index 10ad61db97..ec70497a3a 100644
--- a/ggml/src/ggml-cuda/ggml-cuda.cu
+++ b/ggml/src/ggml-cuda/ggml-cuda.cu
@@ -309,6 +309,19 @@ static ggml_cuda_device_info ggml_cuda_init() {
     // configure logging to stdout
     // CUBLAS_CHECK(cublasLoggerConfigure(1, 1, 0, nullptr));
 
+    for (int id = 0; id < info.device_count; ++id) {
+        ggml_cuda_set_device(id);
+        for (int id_other = 0; id_other < info.device_count; ++id_other) {
+            if (id == id_other) {
+                continue;
+            }
+            int can_access_peer;
+            CUDA_CHECK(cudaDeviceCanAccessPeer(&can_access_peer, id, id_other));
+            if (can_access_peer) {
+                CUDA_CHECK(cudaDeviceEnablePeerAccess(id_other, 0));
+            }
+        }
+    }
     return info;
 }
 
@@ -1371,64 +1384,6 @@ static void ggml_cuda_op_mul_mat_cublas(
     GGML_UNUSED_VARS(dst, src1_ddq_i, src1_padded_row_size);
 }
 
-static void ggml_cuda_set_peer_access(const int n_tokens, int main_device) {
-    static bool peer_access_enabled = false;
-
-    const bool enable_peer_access = n_tokens <= GGML_CUDA_PEER_MAX_BATCH_SIZE;
-
-    if (peer_access_enabled == enable_peer_access) {
-        return;
-    }
-
-#ifdef NDEBUG
-    for (int id = 0; id < ggml_backend_cuda_get_device_count(); ++id) {
-        ggml_cuda_set_device(id);
-        CUDA_CHECK(cudaDeviceSynchronize());
-    }
-
-    for (int id = 0; id < ggml_backend_cuda_get_device_count(); ++id) {
-        ggml_cuda_set_device(id);
-
-        for (int id_other = 0; id_other < ggml_backend_cuda_get_device_count(); ++id_other) {
-            if (id == id_other) {
-                continue;
-            }
-            if (id != main_device && id_other != main_device) {
-                continue;
-            }
-
-            int can_access_peer;
-            CUDA_CHECK(cudaDeviceCanAccessPeer(&can_access_peer, id, id_other));
-            if (can_access_peer) {
-                if (enable_peer_access) {
-                    cudaError_t err = cudaDeviceEnablePeerAccess(id_other, 0);
-                    if (err != cudaErrorPeerAccessAlreadyEnabled) {
-                        CUDA_CHECK(err);
-                    } else {
-                        // reset the error
-                        (void)cudaGetLastError();
-                    }
-                } else {
-                    cudaError_t err = cudaDeviceDisablePeerAccess(id_other);
-                    if (err != cudaErrorPeerAccessNotEnabled) {
-                        CUDA_CHECK(err);
-                    } else {
-                        // reset the error
-                        (void)cudaGetLastError();
-                    }
-                }
-            }
-        }
-    }
-
-    ggml_cuda_set_device(main_device);
-#endif // NDEBUG
-
-    peer_access_enabled = enable_peer_access;
-
-    GGML_UNUSED(main_device);
-}
-
 static cudaError_t ggml_cuda_Memcpy2DPeerAsync(
     void * dst, int dstDevice, size_t dpitch, void * src, int srcDevice, size_t spitch, size_t width, size_t height, cudaStream_t stream) {
 
@@ -2420,11 +2375,6 @@ static void ggml_cuda_mul_mat_id(ggml_backend_cuda_context & ctx, ggml_tensor *
 }
 
 static bool ggml_cuda_compute_forward(ggml_backend_cuda_context & ctx, struct ggml_tensor * dst) {
-    // why is this here instead of mul_mat?
-    if (dst->src[0] != nullptr && ggml_backend_buft_is_cuda_split(dst->src[0]->buffer->buft)) {
-        ggml_cuda_set_peer_access(dst->src[1]->ne[1], ctx.device);
-    }
-
     switch (dst->op) {
         case GGML_OP_ARGMAX:
             ggml_cuda_argmax(ctx, dst);