Commit-ID: 41946c86876ea6a3e8857182356e6d76dbfe7fb6
Gitweb: http://git.kernel.org/tip/41946c86876ea6a3e8857182356e6d76dbfe7fb6
Author: Pan Xinhui <xinhui.pan@xxxxxxxxxxxxxxxxxx>
AuthorDate: Wed, 2 Nov 2016 05:08:31 -0400
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 22 Nov 2016 12:48:06 +0100
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@xxxxxxxxx>
Suggested-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Pan Xinhui <xinhui.pan@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: David.Laight@xxxxxxxxxx
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: benh@xxxxxxxxxxxxxxxxxxx
Cc: borntraeger@xxxxxxxxxx
Cc: bsingharora@xxxxxxxxx
Cc: dave@xxxxxxxxxxxx
Cc: jgross@xxxxxxxx
Cc: kernellwp@xxxxxxxxx
Cc: konrad.wilk@xxxxxxxxxx
Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
Cc: mpe@xxxxxxxxxxxxxx
Cc: paulmck@xxxxxxxxxxxxxxxxxx
Cc: paulus@xxxxxxxxx
Cc: pbonzini@xxxxxxxxxx
Cc: rkrcmar@xxxxxxxxxx
Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: will.deacon@xxxxxxx
Cc: xen-devel-request@xxxxxxxxxxxxxxxxxxxx
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1478077718-37424-5-git-send-email-xinhui.pan@xxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/powerpc/include/asm/spinlock.h | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/powerpc/include/asm/spinlock.h b/arch/powerpc/include/asm/spinlock.h
index fa37fe9..8c1b913 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;
--
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