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x86: kvmclock: drop rdtsc_barrier()

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Drop unnecessary rdtsc_barrier(), as has been determined empirically,
see 057e6a8c66 for details.

Noticed by Andy Lutomirski.

Improves clock_gettime() by approximately 15% on
Intel i7-3520M @ 2.90GHz.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Marcelo Tosatti 2015-04-24 22:36:14 -03:00 committed by Paolo Bonzini
parent d90e3a35e9
commit a3eb97bd80
1 changed files with 0 additions and 1 deletions
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arch/x86/include/asm/pvclock.h
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@ -86,7 +86,6 @@ unsigned __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src,
offset = pvclock_get_nsec_offset(src);
ret = src->system_time + offset;
ret_flags = src->flags;
rdtsc_barrier();
*cycles = ret;
*flags = ret_flags;