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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2015-01-14 17:52:33 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2015-01-23 15:17:04 +0100
commit2c72a44ecdf2a7ceac73844226e97ed2d5dd1e82 (patch)
treea8475e1252115402a27b4c9a822943782085b151 /arch/s390/kernel/early.c
parent55b5eb75e7ccdfe94b6ea1be6bba0c21149abecf (diff)
s390/spinlock: add compare-and-delay to lock wait loops
Add the compare-and-delay instruction to the spin-lock and rw-lock retry loops. A CPU executing the compare-and-delay instruction stops until the lock value has changed. This is done to make the locking code for contended locks to behave better in regard to the multi- hreading facility. A thread of a core executing a compare-and-delay will allow the other threads of a core to get a larger share of the core resources. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel/early.c')
-rw-r--r--arch/s390/kernel/early.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 302ac1f7f8e7..70a329450901 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -393,9 +393,27 @@ 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)
+{
+ S390_lowcore.machine_flags &= ~MACHINE_FLAG_CAD;
+ return 0;
+}
+early_param("nocad", nocad_setup);
+
+static int __init cad_init(void)
+{
+ if (MACHINE_HAS_CAD)
+ /* Enable problem state CAD. */
+ __ctl_set_bit(2, 3);
+ return 0;
+}
+early_initcall(cad_init);
+
static __init void rescue_initrd(void)
{
#ifdef CONFIG_BLK_DEV_INITRD