Do not adjust Minimum Split Depth automatically

Currently minimum split depth is set automatically to 6
when number of CPUs is more than 4. I believe this is a bad
idea since for example my quad (4CPU with hyperthreading) is
detected as 8CPU computer. I've manually lowered down the number
of Threads, but so far I have played all games with Minimum
Split Depth set to 6!

Since 4CPU computers with hyperthreading are quite common and
8 CPU computers extremely rear (I expect we can get a direct
jump to 16 or 32 cores), this automatic adjusting is likely
to do more harm than good. Add a note in Readme.txt, so that
those rear 8CPU owners can manually tweak the "Minimum Split
Depth" parameter

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

diff --git a/Readme.txt b/Readme.txt
index 1a3713985e7cec3e47746503892284cd518f4c64..09216abc21a8b80bf6d1e1ad91214937e8aab905 100644 (file)
--- a/Readme.txt
+++ b/Readme.txt
@@ -14,7 +14,9 @@ number of CPUs on your computer and set the number of search threads
 accordingly, but please be aware that the detection is not always\r
 correct.  It is therefore recommended to inspect the value of the\r
 "Threads" UCI parameter, and to make sure it equals the number of CPU\r
-cores on your computer.\r
+cores on your computer. If you are using more than four threads, it
+is recommended to raise the value of "Minimum Split Depth" UCI parameter
+to 6.
 \r
 \r
 2. Files\r

diff --git a/src/ucioption.cpp b/src/ucioption.cpp
index e25877fe462fdb6801da62e293983f6fae649862..57264166b702fd062dcece96e8ad341a9f9289a3 100644 (file)
--- a/src/ucioption.cpp
+++ b/src/ucioption.cpp
@@ -194,15 +194,6 @@ void init_uci_options() {
 
   options["Threads"].defaultValue = stringify(Min(cpu_count(), 7));
   options["Threads"].currentValue = stringify(Min(cpu_count(), 7));
-
-  // Increase the minimum split depth when the number of CPUs is big.
-  // It would probably be better to let this depend on the number of threads
-  // instead.
-  if (cpu_count() > 4)
-  {
-      options["Minimum Split Depth"].defaultValue = "6";
-      options["Minimum Split Depth"].currentValue = "6";
-  }
 }