forked from Minki/linux
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>
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@ -52,6 +52,14 @@
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#define SYNC_IO
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#endif
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#ifdef CONFIG_PPC_PSERIES
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#define vcpu_is_preempted vcpu_is_preempted
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static inline bool vcpu_is_preempted(int cpu)
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{
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return !!(be32_to_cpu(lppaca_of(cpu).yield_count) & 1);
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}
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#endif
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static __always_inline int arch_spin_value_unlocked(arch_spinlock_t lock)
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{
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return lock.slock == 0;
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