Bias task scheduling towards previous CPU.

Added the option to allow tasks to be scheduled on their previous
CPU if that CPU is not currently executing real-time work.  Helps
preserve cache affinity and reduction in migration costs.  See
CONFIG_CPU_SCHED_BIAS help for more information.

Solution developed by Jonathan Herman.

1 files changed, 18 insertions, 0 deletions

diff --git a/litmus/Kconfig b/litmus/Kconfig
index ad8dc8308cf0..651b66a77c65 100644
--- a/litmus/Kconfig
+++ b/litmus/Kconfig
@@ -36,6 +36,24 @@ config RELEASE_MASTER
 
 endmenu
 
+menu "Performance Hacks"
+
+config CPU_SCHED_BIAS
+        bool "Tasks prefer previous CPU(s)."
+        default n
+        help
+                Allow tasks to be rescheduled on their previously used CPU(s) if that
+                CPU(s) is not currently not executing real-time work.  This may improve
+                performance through the possible preservation of cache affinity.
+
+                Warning: May make bugs harder to find as tasks will migrate less
+                frequently.
+
+                Only bias towards previously used CPU is currently implemented. In the
+                future: bias on CPU topology.
+
+endmenu
+
 menu "Real-Time Synchronization"
 
 config NP_SECTION