s390/spinlock: disabled compare-and-delay by default
Until we have hard performance data about the effects of CAD in the
spinlock loop disable the instruction by default.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 70a3294..4427ab7 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -393,17 +393,19 @@
S390_lowcore.machine_flags |= MACHINE_FLAG_TLB_LC;
if (test_facility(129))
S390_lowcore.machine_flags |= MACHINE_FLAG_VX;
- if (test_facility(128))
- S390_lowcore.machine_flags |= MACHINE_FLAG_CAD;
#endif
}
-static int __init nocad_setup(char *str)
+static int __init cad_setup(char *str)
{
- S390_lowcore.machine_flags &= ~MACHINE_FLAG_CAD;
+ int val;
+
+ get_option(&str, &val);
+ if (val && test_facility(128))
+ S390_lowcore.machine_flags |= MACHINE_FLAG_CAD;
return 0;
}
-early_param("nocad", nocad_setup);
+early_param("cad", cad_setup);
static int __init cad_init(void)
{
