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s390/spinlock: add compare-and-delay to lock wait loops

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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>
This commit is contained in:
Martin Schwidefsky
2015-01-14 17:52:33 +01:00
parent 55b5eb75e7
commit 2c72a44ecd
3 changed files with 66 additions and 7 deletions
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3
arch/s390/include/asm/setup.h
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@@ -57,6 +57,7 @@ extern void detect_memory_memblock(void);
#define MACHINE_FLAG_TE (1UL << 15)
#define MACHINE_FLAG_TLB_LC (1UL << 17)
#define MACHINE_FLAG_VX (1UL << 18)
#define MACHINE_FLAG_CAD (1UL << 19)
#define MACHINE_IS_VM (S390_lowcore.machine_flags & MACHINE_FLAG_VM)
#define MACHINE_IS_KVM (S390_lowcore.machine_flags & MACHINE_FLAG_KVM)
@@ -80,6 +81,7 @@ extern void detect_memory_memblock(void);
#define MACHINE_HAS_TE (0)
#define MACHINE_HAS_TLB_LC (0)
#define MACHINE_HAS_VX (0)
#define MACHINE_HAS_CAD (0)
#else /* CONFIG_64BIT */
#define MACHINE_HAS_IEEE (1)
#define MACHINE_HAS_CSP (1)
@@ -93,6 +95,7 @@ extern void detect_memory_memblock(void);
#define MACHINE_HAS_TE (S390_lowcore.machine_flags & MACHINE_FLAG_TE)
#define MACHINE_HAS_TLB_LC (S390_lowcore.machine_flags & MACHINE_FLAG_TLB_LC)
#define MACHINE_HAS_VX (S390_lowcore.machine_flags & MACHINE_FLAG_VX)
#define MACHINE_HAS_CAD (S390_lowcore.machine_flags & MACHINE_FLAG_CAD)
#endif /* CONFIG_64BIT */
/*