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| author | Pan Xinhui <xinhui.pan@linux.vnet.ibm.com> | 2016-11-02 10:08:31 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-11-22 12:48:06 +0100 |
| commit | 41946c86876ea6a3e8857182356e6d76dbfe7fb6 (patch) | |
| tree | ba90bc806711d5d26dfc05a012718d33c0d34d56 | |
| parent | sched/core: Introduce the vcpu_is_preempted(cpu) interface (diff) | |
| download | linux-41946c86876ea6a3e8857182356e6d76dbfe7fb6.tar.xz linux-41946c86876ea6a3e8857182356e6d76dbfe7fb6.zip | |
locking/core, powerpc: Implement vcpu_is_preempted(cpu)
Optimize spinlock and mutex busy-loops by providing a vcpu_is_preempted(cpu)
function on pSeries. We do not support PowerNV.
All this can be achieved by using lppaca->yield_count, which is zero on PowerNV.
Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: David.Laight@ACULAB.COM
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: benh@kernel.crashing.org
Cc: borntraeger@de.ibm.com
Cc: bsingharora@gmail.com
Cc: dave@stgolabs.net
Cc: jgross@suse.com
Cc: kernellwp@gmail.com
Cc: konrad.wilk@oracle.com
Cc: linuxppc-dev@lists.ozlabs.org
Cc: mpe@ellerman.id.au
Cc: paulmck@linux.vnet.ibm.com
Cc: paulus@samba.org
Cc: pbonzini@redhat.com
Cc: rkrcmar@redhat.com
Cc: virtualization@lists.linux-foundation.org
Cc: will.deacon@arm.com
Cc: xen-devel-request@lists.xenproject.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1478077718-37424-5-git-send-email-xinhui.pan@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | arch/powerpc/include/asm/spinlock.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/spinlock.h b/arch/powerpc/include/asm/spinlock.h index fa37fe93bc02..8c1b913de6d7 100644 --- a/arch/powerpc/include/asm/spinlock.h +++ b/arch/powerpc/include/asm/spinlock.h @@ -52,6 +52,14 @@ #define SYNC_IO #endif +#ifdef CONFIG_PPC_PSERIES +#define vcpu_is_preempted vcpu_is_preempted +static inline bool vcpu_is_preempted(int cpu) +{ + return !!(be32_to_cpu(lppaca_of(cpu).yield_count) & 1); +} +#endif + static __always_inline int arch_spin_value_unlocked(arch_spinlock_t lock) { return lock.slock == 0; |