Commit-ID: 41946c86876ea6a3e8857182356e6d76dbfe7fb6 Gitweb: http://git.kernel.org/tip/41946c86876ea6a3e8857182356e6d76dbfe7fb6 Author: Pan Xinhui <xinhui....@linux.vnet.ibm.com> AuthorDate: Wed, 2 Nov 2016 05:08:31 -0400 Committer: Ingo Molnar <mi...@kernel.org> 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.f...@gmail.com> Suggested-by: Peter Zijlstra (Intel) <pet...@infradead.org> Signed-off-by: Pan Xinhui <xinhui....@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Cc: david.lai...@aculab.com Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: b...@kernel.crashing.org Cc: borntrae...@de.ibm.com Cc: bsinghar...@gmail.com Cc: d...@stgolabs.net Cc: jgr...@suse.com Cc: kernel...@gmail.com Cc: konrad.w...@oracle.com Cc: linuxppc-...@lists.ozlabs.org Cc: m...@ellerman.id.au Cc: paul...@linux.vnet.ibm.com Cc: pau...@samba.org Cc: pbonz...@redhat.com Cc: rkrc...@redhat.com Cc: virtualizat...@lists.linux-foundation.org Cc: will.dea...@arm.com Cc: xen-devel-requ...@lists.xenproject.org Cc: xen-de...@lists.xenproject.org Link: http://lkml.kernel.org/r/1478077718-37424-5-git-send-email-xinhui....@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- 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;
