diff --git a/ggml-metal.m b/ggml-metal.m
index e73fb2517..74a6bff40 100644
--- a/ggml-metal.m
+++ b/ggml-metal.m
@@ -451,13 +451,13 @@ void ggml_metal_graph_compute(
 
     // if there is ctx->concur_list, dispatch concurrently
     // else fallback to serial dispatch
-    MTLComputePassDescriptor * encoder_descriptor = MTLComputePassDescriptor.computePassDescriptor;
-    encoder_descriptor.dispatchType = MTLDispatchTypeSerial;
-    int all_nodes_len = gf->n_nodes;
-    if (ctx->concur_list_len) {
-        encoder_descriptor.dispatchType = MTLDispatchTypeConcurrent;
-        all_nodes_len = ctx->concur_list_len;
-    }
+    MTLComputePassDescriptor * edesc = MTLComputePassDescriptor.computePassDescriptor;
+
+    const bool has_concur = ctx->concur_list_len && ctx->concur_list_len <= GGML_MAX_NODES;
+
+    const int n_nodes  = has_concur ? ctx->concur_list_len      : gf->n_nodes;
+    edesc.dispatchType = has_concur ? MTLDispatchTypeConcurrent : MTLDispatchTypeSerial;
+
     // create multiple command buffers and enqueue them
     // then, we encode the graph into the command buffers in parallel
 
@@ -476,7 +476,7 @@ void ggml_metal_graph_compute(
     dispatch_queue_t queue = dispatch_queue_create("llama.cpp", DISPATCH_QUEUE_CONCURRENT);
 
     for (int cb_idx = 0; cb_idx < n_cb; ++cb_idx) {
-        const int n_nodes_per_cb = (all_nodes_len + n_cb - 1) / n_cb;
+        const int n_nodes_per_cb = (n_nodes + n_cb - 1) / n_cb;
 
         dispatch_async(queue, ^{
             size_t offs_src0 = 0;
@@ -487,22 +487,21 @@ void ggml_metal_graph_compute(
 
             id<MTLComputeCommandEncoder> encoder = nil;
 
-            const int node_start =                                      (cb_idx + 0) * n_nodes_per_cb;
-            const int node_end   = (cb_idx == n_cb - 1) ? all_nodes_len : (cb_idx + 1) * n_nodes_per_cb;
+            const int node_start =                                  (cb_idx + 0) * n_nodes_per_cb;
+            const int node_end   = (cb_idx == n_cb - 1) ? n_nodes : (cb_idx + 1) * n_nodes_per_cb;
 
             for (int ind = node_start; ind < node_end; ++ind) {
-                int i = ind;
-                if (ctx->concur_list_len) {
-                    i = ctx->concur_list[ind];
-                }
+                const int i = has_concur ? ctx->concur_list[ind] : ind;
+
                 if (i == -1) {
                     if (encoder == nil) {
-                        encoder = [command_buffer computeCommandEncoderWithDescriptor: encoder_descriptor];
+                        encoder = [command_buffer computeCommandEncoderWithDescriptor: edesc];
                         continue;
                     }
                     [encoder memoryBarrierWithScope:MTLBarrierScopeBuffers];
                     continue;
                 }
+
                 metal_printf("%s: encoding node %3d, op = %8s\n", __func__, i, ggml_op_name(gf->nodes[i]->op));
 
                 struct ggml_tensor * src0 = gf->nodes[i]->src[0];
@@ -573,7 +572,7 @@ void ggml_metal_graph_compute(
                     case GGML_OP_ADD:
                         {
                             if (encoder == nil) {
-                                encoder = [command_buffer computeCommandEncoderWithDescriptor: encoder_descriptor];
+                                encoder = [command_buffer computeCommandEncoderWithDescriptor: edesc];
                             }
 
                             if (ggml_nelements(src1) == ne10) {
@@ -594,7 +593,7 @@ void ggml_metal_graph_compute(
                     case GGML_OP_MUL:
                         {
                             if (encoder == nil) {
-                                encoder = [command_buffer computeCommandEncoderWithDescriptor: encoder_descriptor];
+                                encoder = [command_buffer computeCommandEncoderWithDescriptor: edesc];
                             }
 
                             if (ggml_nelements(src1) == ne10) {
@@ -615,7 +614,7 @@ void ggml_metal_graph_compute(
                     case GGML_OP_SCALE:
                         {
                             if (encoder == nil) {
-                                encoder = [command_buffer computeCommandEncoderWithDescriptor: encoder_descriptor];
+                                encoder = [command_buffer computeCommandEncoderWithDescriptor: edesc];
                             }
 
                             const float scale = *(const float *) src1->data;
@@ -634,7 +633,7 @@ void ggml_metal_graph_compute(
                             case GGML_UNARY_OP_SILU:
                                 {
                                     if (encoder == nil) {
-                                        encoder = [command_buffer computeCommandEncoderWithDescriptor: encoder_descriptor];
+                                        encoder = [command_buffer computeCommandEncoderWithDescriptor: edesc];
                                     }
 
                                     [encoder setComputePipelineState:ctx->pipeline_silu];
@@ -648,7 +647,7 @@ void ggml_metal_graph_compute(
                             case GGML_UNARY_OP_RELU:
                                 {
                                     if (encoder == nil) {
-                                        encoder = [command_buffer computeCommandEncoderWithDescriptor: encoder_descriptor];
+                                        encoder = [command_buffer computeCommandEncoderWithDescriptor: edesc];
                                     }
 
                                     [encoder setComputePipelineState:ctx->pipeline_relu];
@@ -662,7 +661,7 @@ void ggml_metal_graph_compute(
                             case GGML_UNARY_OP_GELU:
                                 {
                                     if (encoder == nil) {
-                                        encoder = [command_buffer computeCommandEncoderWithDescriptor: encoder_descriptor];
+                                        encoder = [command_buffer computeCommandEncoderWithDescriptor: edesc];
                                     }
 
                                     [encoder setComputePipelineState:ctx->pipeline_gelu];
@@ -682,7 +681,7 @@ void ggml_metal_graph_compute(
                     case GGML_OP_SOFT_MAX:
                         {
                             if (encoder == nil) {
-                                encoder = [command_buffer computeCommandEncoderWithDescriptor: encoder_descriptor];
+                                encoder = [command_buffer computeCommandEncoderWithDescriptor: edesc];
                             }
 
                             const int nth = 32;
@@ -700,7 +699,7 @@ void ggml_metal_graph_compute(
                     case GGML_OP_DIAG_MASK_INF:
                         {
                             if (encoder == nil) {
-                                encoder = [command_buffer computeCommandEncoderWithDescriptor: encoder_descriptor];
+                                encoder = [command_buffer computeCommandEncoderWithDescriptor: edesc];
                             }
 
                             const int n_past = ((int32_t *)(dst->op_params))[0];
@@ -763,7 +762,7 @@ void ggml_metal_graph_compute(
                                 }
                             } else {
                                 if (encoder == nil) {
-                                    encoder = [command_buffer computeCommandEncoderWithDescriptor: encoder_descriptor];
+                                    encoder = [command_buffer computeCommandEncoderWithDescriptor: edesc];
                                 }
 
                                 int nth0 = 32;
@@ -890,7 +889,7 @@ void ggml_metal_graph_compute(
                     case GGML_OP_GET_ROWS:
                         {
                             if (encoder == nil) {
-                                encoder = [command_buffer computeCommandEncoderWithDescriptor: encoder_descriptor];
+                                encoder = [command_buffer computeCommandEncoderWithDescriptor: edesc];
                             }
 
                             switch (src0->type) {
@@ -919,7 +918,7 @@ void ggml_metal_graph_compute(
                     case GGML_OP_RMS_NORM:
                         {
                             if (encoder == nil) {
-                                encoder = [command_buffer computeCommandEncoderWithDescriptor: encoder_descriptor];
+                                encoder = [command_buffer computeCommandEncoderWithDescriptor: edesc];
                             }
 
                             float eps;
@@ -942,7 +941,7 @@ void ggml_metal_graph_compute(
                     case GGML_OP_NORM:
                         {
                             if (encoder == nil) {
-                                encoder = [command_buffer computeCommandEncoderWithDescriptor: encoder_descriptor];
+                                encoder = [command_buffer computeCommandEncoderWithDescriptor: edesc];
                             }
 
                             const float eps = 1e-5f;
@@ -964,7 +963,7 @@ void ggml_metal_graph_compute(
                     case GGML_OP_ALIBI:
                         {
                             if (encoder == nil) {
-                                encoder = [command_buffer computeCommandEncoderWithDescriptor: encoder_descriptor];
+                                encoder = [command_buffer computeCommandEncoderWithDescriptor: edesc];
                             }
 
                             GGML_ASSERT((src0t == GGML_TYPE_F32));
@@ -1007,7 +1006,7 @@ void ggml_metal_graph_compute(
                     case GGML_OP_ROPE:
                         {
                             if (encoder == nil) {
-                                encoder = [command_buffer computeCommandEncoderWithDescriptor: encoder_descriptor];
+                                encoder = [command_buffer computeCommandEncoderWithDescriptor: edesc];
                             }
 
                             const int n_past = ((int32_t *) dst->op_params)[0];
@@ -1051,7 +1050,7 @@ void ggml_metal_graph_compute(
                     case GGML_OP_CONT:
                         {
                             if (encoder == nil) {
-                                encoder = [command_buffer computeCommandEncoderWithDescriptor: encoder_descriptor];
+                                encoder = [command_buffer computeCommandEncoderWithDescriptor: edesc];
                             }
 
                             const int nth = 32;