[PATCH v2] sched: print information about scheduling granularity

[Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>]

Currently it might be not obvious which scheduling mode (e.g. core-
scheduling) is being used by the scheduler. Alleviate this by printing
additional information about the selected granularity per-cpupool.

Note: per-cpupool granularity selection is not implemented yet.
      The single global value is being used for each cpupool.

Signed-off-by: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>
---
v2:
- print information on a separate line
- use per-cpupool granularity
- updated commit message

CC: Juergen Gross <jgross@xxxxxxxx>
CC: Dario Faggioli <dfaggioli@xxxxxxxx>
CC: George Dunlap <george.dunlap@xxxxxxxxxx>
CC: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/common/sched/cpupool.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/xen/common/sched/cpupool.c b/xen/common/sched/cpupool.c
index d40345b585..68106f6c15 100644
--- a/xen/common/sched/cpupool.c
+++ b/xen/common/sched/cpupool.c
@@ -40,6 +40,30 @@ static DEFINE_SPINLOCK(cpupool_lock);
 static enum sched_gran __read_mostly opt_sched_granularity = SCHED_GRAN_cpu;
 static unsigned int __read_mostly sched_granularity = 1;
 
+static void sched_gran_print(enum sched_gran mode, unsigned int gran)
+{
+    char *str = "";
+
+    switch ( mode )
+    {
+    case SCHED_GRAN_cpu:
+        str = "cpu";
+        break;
+    case SCHED_GRAN_core:
+        str = "core";
+        break;
+    case SCHED_GRAN_socket:
+        str = "socket";
+        break;
+    default:
+        ASSERT_UNREACHABLE();
+        break;
+    }
+
+    printk("Scheduling granularity: %s, %u CPU%s per sched-resource\n",
+           str, gran, gran == 1 ? "" : "s");
+}
+
 #ifdef CONFIG_HAS_SCHED_GRANULARITY
 static int __init sched_select_granularity(const char *str)
 {
@@ -115,6 +139,7 @@ static void __init cpupool_gran_init(void)
         warning_add(fallback);
 
     sched_granularity = gran;
+    sched_gran_print(opt_sched_granularity, sched_granularity);
 }
 
 unsigned int cpupool_get_granularity(const struct cpupool *c)
@@ -911,6 +936,7 @@ void dump_runq(unsigned char key)
     {
         printk("Cpupool %d:\n", (*c)->cpupool_id);
         printk("Cpus: %*pbl\n", CPUMASK_PR((*c)->cpu_valid));
+        sched_gran_print((*c)->gran, cpupool_get_granularity(*c));
         schedule_dump(*c);
     }
 
-- 
2.17.1