From: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
linuxppc-dev@lists.ozlabs.org
Cc: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au,
peterz@infradead.org, mingo@redhat.com,
paulmck@linux.vnet.ibm.com, waiman.long@hpe.com, mnipxh@163.com,
boqun.feng@gmail.com, Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Subject: [PATCH v2 3/6] powerpc: lib/locks.c: cpu yield/wake helper function
Date: Tue, 17 May 2016 15:49:44 +0800 [thread overview]
Message-ID: <1463471387-5115-4-git-send-email-xinhui.pan@linux.vnet.ibm.com> (raw)
In-Reply-To: <1463471387-5115-1-git-send-email-xinhui.pan@linux.vnet.ibm.com>
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 <xinhui.pan@linux.vnet.ibm.com>
---
arch/powerpc/include/asm/spinlock.h | 4 ++++
arch/powerpc/lib/locks.c | 32 ++++++++++++++++++++++++++++++++
2 files changed, 36 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..4109679a 100644
--- a/arch/powerpc/lib/locks.c
+++ b/arch/powerpc/lib/locks.c
@@ -23,6 +23,38 @@
#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_CEDE);
+ return;
+ }
+ 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 */
+ rmb();
+ 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 */
+ rmb();
+ 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)
{
--
1.9.1
next prev parent reply other threads:[~2016-05-17 7:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-17 7:49 [PATCH v3 0/6] powerpc use pv-qpsinlock instead of spinlock Pan Xinhui
2016-05-17 7:49 ` [PATCH v2 1/6] qspinlock: powerpc support qspinlock Pan Xinhui
2016-05-17 7:49 ` [PATCH v2 2/6] powerpc: pseries/Kconfig: qspinlock build config Pan Xinhui
2016-05-17 7:49 ` Pan Xinhui [this message]
2016-05-17 7:49 ` [PATCH v2 4/6] pv-qspinlock: powerpc support pv-qspinlock Pan Xinhui
2016-05-17 7:49 ` [PATCH v2 5/6] pv-qspinlock: use cmpxchg_release in __pv_queued_spin_unlock Pan Xinhui
2016-05-17 7:49 ` [PATCH v2 6/6] powerpc: pseries: pv-qspinlock build config/make Pan Xinhui
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