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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2015-02-19 17:53:16 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2015-02-19 18:05:38 +0100
commit61b0b01686d482205db14987826e1a11dd17d65c (patch)
tree6231308c7dbff1ad58e66de14ff5872d61d3577d
parent4ba2815d3bf38d6a959d2d11b08cf862550dcfcc (diff)
downloadlinux-61b0b01686d482205db14987826e1a11dd17d65c.tar.bz2
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>
-rw-r--r--arch/s390/kernel/early.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 70a329450901..4427ab7ac23a 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -393,17 +393,19 @@ static __init void detect_machine_facilities(void)
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)
{