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51c19b4f59
Improve performance of time system calls when using Linux pvclock, by reading time info from fixmap visible copy of pvclock data. Originally from Jeremy Fitzhardinge. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
30 lines
625 B
C
30 lines
625 B
C
/*
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* Copyright 2006 Andi Kleen, SUSE Labs.
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* Subject to the GNU Public License, v.2
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*
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* Fast user context implementation of getcpu()
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*/
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#include <linux/kernel.h>
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#include <linux/getcpu.h>
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#include <linux/jiffies.h>
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#include <linux/time.h>
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#include <asm/vsyscall.h>
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#include <asm/vgtod.h>
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notrace long
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__vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
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{
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unsigned int p;
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p = __getcpu();
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if (cpu)
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*cpu = p & VGETCPU_CPU_MASK;
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if (node)
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*node = p >> 12;
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return 0;
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}
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long getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
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__attribute__((weak, alias("__vdso_getcpu")));
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