On Wed, Oct 31, 2012 at 08:46:58PM -0200, Marcelo Tosatti wrote: > Originally from Jeremy Fitzhardinge. > > pvclock_get_time_values, which contains the memory barriers > will be removed by next patch. > > Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx> > > Index: vsyscall/arch/x86/kernel/pvclock.c > =================================================================== > --- vsyscall.orig/arch/x86/kernel/pvclock.c > +++ vsyscall/arch/x86/kernel/pvclock.c > @@ -97,10 +97,10 @@ cycle_t pvclock_clocksource_read(struct > > do { > version = pvclock_get_time_values(&shadow, src); > - barrier(); > + rdtsc_barrier(); > offset = pvclock_get_nsec_offset(&shadow); > ret = shadow.system_timestamp + offset; > - barrier(); > + rdtsc_barrier(); > } while (version != src->version); > > if ((valid_flags & PVCLOCK_TSC_STABLE_BIT) && > On a guest without SSE2 rdtsc_barrier() will be nop while rmb() will be "lock; addl $0,0(%%esp)". I doubt pvclock will work correctly either way though. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html