From a3eb97bd80134ba07864ca00747466c02118aca1 Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Fri, 24 Apr 2015 22:36:14 -0300 Subject: [PATCH] x86: kvmclock: drop rdtsc_barrier() Drop unnecessary rdtsc_barrier(), as has been determined empirically, see 057e6a8c660e95c3f4e7162e00e2fee1fc90c50d for details. Noticed by Andy Lutomirski. Improves clock_gettime() by approximately 15% on Intel i7-3520M @ 2.90GHz. Signed-off-by: Marcelo Tosatti Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/pvclock.h | 1 - 1 file changed, 1 deletion(-) diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h index d6b078e9fa28..628954ceede1 100644 --- a/arch/x86/include/asm/pvclock.h +++ b/arch/x86/include/asm/pvclock.h @@ -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; -- 2.20.1