From 17a2b4a31533193d3d3ee50a0a0ca85403aa53cc Mon Sep 17 00:00:00 2001
From: fszontagh <51741446+fszontagh@users.noreply.github.com>
Date: Mon, 8 Jun 2026 15:53:54 +0200
Subject: [PATCH] perf: cap planner budget when model dwarfs the streaming
 budget (#1612)

---
 src/core/ggml_extend.hpp | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/core/ggml_extend.hpp b/src/core/ggml_extend.hpp
index 7dc37cb9..f78e6cd6 100644
--- a/src/core/ggml_extend.hpp
+++ b/src/core/ggml_extend.hpp
@@ -2470,10 +2470,26 @@ protected:
             *effective_budget_out = effective_budget;
         }
 
+        // When streaming and the model dwarfs the budget, cap the planner at
+        // a quarter so it builds smaller merged segments and chunk-K can fit
+        // alongside. Without streaming the cap only adds dispatch overhead.
+        size_t planner_budget = effective_budget;
+        if (stream_layers_enabled) {
+            size_t total_params_bytes = 0;
+            for (const ggml_tensor* t : params_tensor_set_) {
+                if (t != nullptr) {
+                    total_params_bytes += ggml_nbytes(t);
+                }
+            }
+            if (total_params_bytes * 4 > effective_budget * 3) {
+                planner_budget = effective_budget / 4;
+            }
+        }
+
         *plan_out = sd::ggml_graph_cut::resolve_plan(runtime_backend,
                                                      gf,
                                                      &graph_cut_plan_cache_,
-                                                     effective_budget,
+                                                     planner_budget,
                                                      params_tensor_set_,
                                                      get_desc().c_str());
         if (stream_layers_enabled) {