IID margin reduced to 128

Chess13234 · snicolet · commit 62937d1007e0 · 2018-03-24T08:59:48.000+01:00
Change the internal iterative deepening margin from +256 to +128. Passed STC: LLR: 3.26 (-2.94,2.94) [0.00,5.00] Total: 22006 W: 4646 L: 4400 D: 12960 http://tests.stockfishchess.org/tests/view/5ab54a240ebc590295d8847d Passed LTC: LLR: 2.96 (-2.94,2.94) [0.00,4.00] Total: 46665 W: 7187 L: 6898 D: 32580 http://tests.stockfishchess.org/tests/view/5ab5ba690ebc590295d884b4 Possible work in this area after this change: • Reduce even more the margin? • Try to do IID for smaller depths too? Bench: 5851102
diff --git a/src/search.cpp b/src/search.cpp
@@ -791,7 +791,7 @@ namespace {
     // Step 11. Internal iterative deepening (skipped when in check)
     if (    depth >= 6 * ONE_PLY
         && !ttMove
-        && (PvNode || ss->staticEval + 256 >= beta))
+        && (PvNode || ss->staticEval + 128 >= beta))
     {
         Depth d = 3 * depth / 4 - 2 * ONE_PLY;
         search<NT>(pos, ss, alpha, beta, d, cutNode, true);

Original file line number	Diff line number	Diff line change
`@@ -791,7 +791,7 @@ namespace {`
`791`	`791`	`// Step 11. Internal iterative deepening (skipped when in check)`
`792`	`792`	`if ( depth >= 6 * ONE_PLY`
`793`	`793`	`&& !ttMove`
`794`		`- && (PvNode \|\| ss->staticEval + 256 >= beta))`
	`794`	`+ && (PvNode \|\| ss->staticEval + 128 >= beta))`
`795`	`795`	`{`
`796`	`796`	`Depth d = 3 * depth / 4 - 2 * ONE_PLY;`
`797`	`797`	`search<NT>(pos, ss, alpha, beta, d, cutNode, true);`