From: Pierre Ossman <ossman@cendio.se>
Date: Fri, 20 Nov 2015 15:14:48 +0000 (+0100)
Subject: Limit the number of decoder threads to 4
X-Git-Tag: v1.6.90~95^2~2
X-Git-Url: https://source.dussan.org/?a=commitdiff_plain;h=a0eb1e8af915201a260bac19d33fee76faf665ca;p=tigervnc.git

Limit the number of decoder threads to 4

They just end up burning CPU fighting each other without much
improvement to the decoding time beyond four threads.
---

diff --git a/common/rfb/DecodeManager.cxx b/common/rfb/DecodeManager.cxx
index d6c3b0b5..d7cffcfd 100644
--- a/common/rfb/DecodeManager.cxx
+++ b/common/rfb/DecodeManager.cxx
@@ -51,7 +51,12 @@ DecodeManager::DecodeManager(CConnection *conn) :
     vlog.error("Unable to determine the number of CPU cores on this system");
     cpuCount = 1;
   } else {
-    vlog.info("Detected %d CPU core(s) available for decoding", (int)cpuCount);
+    vlog.info("Detected %d CPU core(s)", (int)cpuCount);
+    // No point creating more threads than this, they'll just end up
+    // wasting CPU fighting for locks
+    if (cpuCount > 4)
+      cpuCount = 4;
+    vlog.info("Creating %d decoder thread(s)", (int)cpuCount);
   }
 
   while (cpuCount--) {