Re: x86: kvmclock: drop rdtsc_barrier()
On Fri, Apr 24, 2015 at 10:36:14PM -0300, Marcelo Tosatti wrote: > > 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 > > diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h > index 25b1cc0..a5beb23 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; > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html Ping? -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: x86: kvmclock: drop rdtsc_barrier()
On 04/24/2015 09:36 PM, Marcelo Tosatti wrote: > > 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 Acked-by: Rik van Riel -- All rights reversed -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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 diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h index 25b1cc0..a5beb23 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; -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
