xen: sched: per-core runqueues as default in credit2

Experiments have shown that arranging the scheduing
runqueues on a per-core basis yields better results,
in most cases.

Such evaluation has been done, for the first time,
by Uma Sharma, during her participation to OPW. Some
of the results she got are summarized here:

 http://lists.xen.org/archives/html/xen-devel/2015-03/msg01499.html

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
Signed-off-by: Uma Sharma <uma.sharma523@gmail.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>

diff --git a/docs/misc/xen-command-line.markdown b/docs/misc/xen-command-line.markdown
index 0047f94f525060a472a46c61ee7e9e5bf21d483f..5d801b85b8e9be1304bab8aadbdafc880fbf5426 100644 (file)
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -472,7 +472,7 @@ combination with the `low_crashinfo` command line option.
 ### credit2\_runqueue
 > `= core | socket | node | all`
 
-> Default: `socket`
+> Default: `core`
 
 Specify how host CPUs are arranged in runqueues. Runqueues are kept
 balanced with respect to the load generated by the vCPUs running on

diff --git a/xen/common/sched_credit2.c b/xen/common/sched_credit2.c
index d43f67ac97c6f03e9341a86fbcdd5c0009ae3cb6..6be66ee0de376123e18df4d91ea1c21657e30290 100644 (file)
--- a/xen/common/sched_credit2.c
+++ b/xen/common/sched_credit2.c
@@ -226,7 +226,7 @@ static const char *const opt_runqueue_str[] = {
     [OPT_RUNQUEUE_NODE] = "node",
     [OPT_RUNQUEUE_ALL] = "all"
 };
-static int __read_mostly opt_runqueue = OPT_RUNQUEUE_SOCKET;
+static int __read_mostly opt_runqueue = OPT_RUNQUEUE_CORE;
 
 static void parse_credit2_runqueue(const char *s)
 {