From 6bf7f3f41ca9956210a604a29dcfc131410803f0 Mon Sep 17 00:00:00 2001
From: Francis Couture-Harpin <git@compilade.net>
Date: Mon, 18 Mar 2024 00:35:03 -0400
Subject: [PATCH] ggml : do not multi-thread ops returning empty tensors

---
 ggml.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/ggml.c b/ggml.c
index 1028f18b8..ed2cbe30f 100644
--- a/ggml.c
+++ b/ggml.c
@@ -17935,6 +17935,12 @@ static void ggml_graph_compute_perf_stats_node(struct ggml_tensor * node, const
 static int ggml_get_n_tasks(struct ggml_tensor * node, int n_threads, int n_cur_threads) {
     int n_tasks = 0;
 
+    if (ggml_is_empty(node)) {
+        // no need to multi-thread a no-op
+        n_tasks = 1;
+        return n_tasks;
+    }
+
     switch (node->op) {
         case GGML_OP_CPY:
         case GGML_OP_DUP:
@@ -18017,7 +18023,7 @@ static int ggml_get_n_tasks(struct ggml_tensor * node, int n_threads, int n_cur_
             {
                 // FIXME: the cost of launching additional threads decreases performance with GPU offloading
                 //n_tasks = MIN(n_threads, ggml_nelements(node->src[1]));
-                n_tasks = MIN(n_cur_threads, MAX(ggml_nelements(node->src[1]), 1));
+                n_tasks = MIN(n_cur_threads, ggml_nelements(node->src[1]));
             } break;
         case GGML_OP_SCALE:
         case GGML_OP_SET: