From 8ecfc3c89d48418f84864fb235635d69e6ea37b8 Mon Sep 17 00:00:00 2001
From: Stefan Geschwentner <stgeschwentner@gmail.com>
Date: Sun, 17 Aug 2025 08:38:16 +0200
Subject: [PATCH] Bigger thread dependent initial window.

Increase the initial delta of the aspiration window  by "thread id mod 8".

Passed SMP STC:
LLR: 2.96 (-2.94,2.94) <0.00,2.00>
Total: 106176 W: 27470 L: 27069 D: 51637
Ptnml(0-2): 121, 12032, 28386, 12423, 126
https://tests.stockfishchess.org/tests/view/68a178fab6fb3300203bbaec

Passed SMP LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 133076 W: 34272 L: 33772 D: 65032
Ptnml(0-2): 38, 13709, 38537, 14223, 31
https://tests.stockfishchess.org/tests/view/68a1b5d2b6fb3300203bbb71

closes https://github.com/official-stockfish/Stockfish/pull/6239

No functional change
---
 src/search.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/search.cpp b/src/search.cpp
index aa78a673f..446f81379 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -322,7 +322,7 @@ void Search::Worker::iterative_deepening() {
             selDepth = 0;
 
             // Reset aspiration window starting size
-            delta     = 5 + std::abs(rootMoves[pvIdx].meanSquaredScore) / 11131;
+            delta     = 5 + threadIdx % 8 + std::abs(rootMoves[pvIdx].meanSquaredScore) / 11131;
             Value avg = rootMoves[pvIdx].averageScore;
             alpha     = std::max(avg - delta, -VALUE_INFINITE);
             beta      = std::min(avg + delta, VALUE_INFINITE);