From f2da0ccf3f82c663daf958d05243d75247de6eb2 Mon Sep 17 00:00:00 2001
From: Shawn Xu <xu107288696@gmail.com>
Date: Sun, 24 Aug 2025 15:47:51 -0700
Subject: [PATCH] Simplify SMP Reduction

Passed Non-regression SMP STC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 232784 W: 59845 L: 59841 D: 113098
Ptnml(0-2): 289, 26459, 62934, 26379, 331
https://tests.stockfishchess.org/tests/view/68ab96bf75da51a345a5acd6

Passed Non-regression SMP LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 374270 W: 95978 L: 96113 D: 182179
Ptnml(0-2): 118, 38575, 109888, 38432, 122
https://tests.stockfishchess.org/tests/view/68abcf1c75da51a345a5adb6

closes https://github.com/official-stockfish/Stockfish/pull/6285

Bench: 2667107
---
 src/search.cpp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/search.cpp b/src/search.cpp
index 634492682..5a0185618 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1167,8 +1167,7 @@ moves_loop:  // When in check, search starts here
 
         // These reduction adjustments have no proven non-linear scaling
 
-        r += 671;  // Base reduction offset to compensate for other tweaks
-        r -= (threadIdx % 8) * 64;
+        r += 543;  // Base reduction offset to compensate for other tweaks
         r -= moveCount * 66;
         r -= std::abs(correctionValue) / 30450;