From 61b0b01686d482205db14987826e1a11dd17d65c Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Thu, 19 Feb 2015 17:53:16 +0100 Subject: [PATCH] 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 --- arch/s390/kernel/early.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) 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 @@ 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) { -- 2.7.4