Major improvements in algoritms of CPU load balancing. This should
make polling cycles more regular and changes in CPU load more smooth.
git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@497 3789f03b-4d11-0410-bbf8-ca57d06f2519
diff --git a/x0vncserver/PollingScheduler.cxx b/x0vncserver/PollingScheduler.cxx
index af597df..c9d8d60 100644
--- a/x0vncserver/PollingScheduler.cxx
+++ b/x0vncserver/PollingScheduler.cxx
@@ -23,6 +23,10 @@
#include <string.h>
#include <stdlib.h>
+#ifdef DEBUG
+#include <stdio.h>
+#endif
+
#include <x0vncserver/PollingScheduler.h>
PollingScheduler::PollingScheduler(int interval, int maxload)
@@ -69,6 +73,7 @@
memset(m_slept, 0, sizeof(m_slept));
m_sleptSum = 0;
m_idx = 0;
+ m_count = 0;
} else {
@@ -95,26 +100,63 @@
m_errorAbsSum = m_errorAbsSum - abs(oldest) + abs(newError);
//
- // Here is the most important part.
+ // Below is the most important part.
// Compute desired duration of the upcoming polling pass.
//
- m_ratedDuration = m_interval - m_errorSum;
- int optimalLoadDuration =
- ((m_durationSum - m_sleptSum) * 900 + m_maxload * 4) / (m_maxload * 8)
- - m_durationSum;
+ // Estimation based on keeping up constant interval.
+ m_ratedDuration = m_interval - m_errorSum / 2;
+ // Estimations based on keeping up desired CPU load.
+ int optimalLoadDuration1 = 0;
+ int optimalLoadDuration8 = 0;
+ int optimalLoadDuration = 0;
+
+ if (m_count > 4) {
+ // Estimation 1 (use previous pass statistics).
+ optimalLoadDuration1 =
+ ((duration - m_sleptThisPass) * 100 + m_maxload/2) / m_maxload;
+
+ if (m_count > 16) {
+ // Estimation 2 (use history of 8 previous passes).
+ optimalLoadDuration8 =
+ ((m_durationSum - m_sleptSum) * 900 + m_maxload*4) / (m_maxload*8)
+ - m_durationSum;
+ // Mix the above two giving more priority to the first.
+ optimalLoadDuration =
+ (2 * optimalLoadDuration1 + optimalLoadDuration8) / 3;
+ } else {
+ optimalLoadDuration = optimalLoadDuration1;
+ }
+ }
+
+#ifdef DEBUG
+ fprintf(stderr, "<est %3d,%3d,%d>\t",
+ m_ratedDuration, optimalLoadDuration1, optimalLoadDuration8);
+#endif
+
+ // Choose final estimation.
if (m_ratedDuration < optimalLoadDuration) {
m_ratedDuration = optimalLoadDuration;
}
-
if (m_ratedDuration < 0) {
m_ratedDuration = 0;
+ } else if (m_ratedDuration > 500 && m_interval <= 100) {
+ m_ratedDuration = 500;
+ } else if (m_ratedDuration > 1000) {
+ m_ratedDuration = 1000;
}
- // Update ring buffer indexer (8 elements in the arrays).
+#ifdef DEBUG
+ fprintf(stderr, "<final est %3d>\t", m_ratedDuration);
+#endif
+
+ // Update ring buffer indexer (8 elements per each arrays).
m_idx = (m_idx + 1) & 7;
+ // Update pass counter.
+ m_count++;
+
}
m_passStarted = timeNow;