[PATCH v3 3/6] powerpc: lib/locks.c: Add cpu yield/wake helper function
From: Pan Xinhui <hidden>
Date: 2016-05-25 08:22:02
Also in:
linuxppc-dev, lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), locking primitives, the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Peter Zijlstra, Ingo Molnar, Will Deacon, Boqun Feng, Linus Torvalds
pv-qspinlock core has pv_wait/pv_kick which will give a better performace by yielding and kicking cpu at some cases. lets support them by adding two corresponding helper functions. Signed-off-by: Pan Xinhui <redacted> --- arch/powerpc/include/asm/spinlock.h | 4 ++++ arch/powerpc/lib/locks.c | 33 +++++++++++++++++++++++++++++++++ 2 files changed, 37 insertions(+)
diff --git a/arch/powerpc/include/asm/spinlock.h b/arch/powerpc/include/asm/spinlock.h
index 4359ee6..3b65372 100644
--- a/arch/powerpc/include/asm/spinlock.h
+++ b/arch/powerpc/include/asm/spinlock.h@@ -56,9 +56,13 @@ /* We only yield to the hypervisor if we are in shared processor mode */ #define SHARED_PROCESSOR (lppaca_shared_proc(local_paca->lppaca_ptr)) extern void __spin_yield(arch_spinlock_t *lock); +extern void __spin_yield_cpu(int cpu); +extern void __spin_wake_cpu(int cpu); extern void __rw_yield(arch_rwlock_t *lock); #else /* SPLPAR */ #define __spin_yield(x) barrier() +#define __spin_yield_cpu(x) barrier() +#define __spin_wake_cpu(x) barrier() #define __rw_yield(x) barrier() #define SHARED_PROCESSOR 0 #endif
diff --git a/arch/powerpc/lib/locks.c b/arch/powerpc/lib/locks.c
index a9ebd71..3a58834 100644
--- a/arch/powerpc/lib/locks.c
+++ b/arch/powerpc/lib/locks.c@@ -23,6 +23,39 @@ #include <asm/hvcall.h> #include <asm/smp.h> +void __spin_yield_cpu(int cpu) +{ + unsigned int holder_cpu = cpu, yield_count; + + if (cpu == -1) { + plpar_hcall_norets(H_CONFER, -1, 0); + return; + } + BUG_ON(holder_cpu >= nr_cpu_ids); + yield_count = be32_to_cpu(lppaca_of(holder_cpu).yield_count); + if ((yield_count & 1) == 0) { + /* if target cpu is running, confer slices to lpar*/ + plpar_hcall_norets(H_CONFER, -1, 0); + return; + } + plpar_hcall_norets(H_CONFER, + get_hard_smp_processor_id(holder_cpu), yield_count); +} +EXPORT_SYMBOL_GPL(__spin_yield_cpu); + +void __spin_wake_cpu(int cpu) +{ + unsigned int holder_cpu = cpu, yield_count; + + BUG_ON(holder_cpu >= nr_cpu_ids); + yield_count = be32_to_cpu(lppaca_of(holder_cpu).yield_count); + if ((yield_count & 1) == 0) + return; /* virtual cpu is currently running */ + plpar_hcall_norets(H_PROD, + get_hard_smp_processor_id(holder_cpu)); +} +EXPORT_SYMBOL_GPL(__spin_wake_cpu); + #ifndef CONFIG_QUEUED_SPINLOCKS void __spin_yield(arch_spinlock_t *lock) {
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1.9.1