[S390] topology: add SCHED_MC config option

This allows us to easily check for performance differences seen with
!CONFIG_SCHED_MC and topology=off.
Actually there shouldn't be any (besides a small overhead because of
additional code).

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 12 insertions, 1 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 97146ab157e6..45a9bed4a3fb 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -196,9 +196,18 @@ config HOTPLUG_CPU
           can be controlled through /sys/devices/system/cpu/cpu#.
           Say N if you want to disable CPU hotplug.
 
+config SCHED_MC
+        def_bool y
+        prompt "Multi-core scheduler support"
+        depends on SMP
+        help
+          Multi-core scheduler support improves the CPU scheduler's decision
+          making when dealing with multi-core CPU chips at a cost of slightly
+          increased overhead in some places.
+
 config SCHED_BOOK
         bool "Book scheduler support"
-        depends on SMP
+        depends on SMP && SCHED_MC
         help
           Book scheduler support improves the CPU scheduler's decision making
           when dealing with machines that have several books.
diff --git a/arch/s390/kernel/sysinfo.c b/arch/s390/kernel/sysinfo.c
index f04d93aa48ec..5c9e439bf3f6 100644
--- a/arch/s390/kernel/sysinfo.c
+++ b/arch/s390/kernel/sysinfo.c
@@ -106,11 +106,13 @@ static int stsi_15_1_x(struct sysinfo_15_1_x *info, char *page, int len)
         for (i = 0; i < TOPOLOGY_NR_MAG; i++)
                 len += sprintf(page + len, " %d", info->mag[i]);
         len += sprintf(page + len, "\n");
+#ifdef CONFIG_SCHED_MC
         store_topology(info);
         len += sprintf(page + len, "CPU Topology SW:     ");
         for (i = 0; i < TOPOLOGY_NR_MAG; i++)
                 len += sprintf(page + len, " %d", info->mag[i]);
         len += sprintf(page + len, "\n");
+#endif
         return len;
 }