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Re: [Xen-devel] [Xen-users] Re: Xen 4 TSC problems



in the meantime, it would be cool to have a kernel boot parameter that could 
disable this wrapping'
correction' ? like <check-timer-wrap=false>

> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxx [mailto:xen-devel-
> bounces@xxxxxxxxxxxxx] On Behalf Of Ian Campbell
> Sent: Thursday, October 18, 2012 9:40 AM
> To: Keir Fraser
> Cc: Jeremy Fitzhardinge; xen-devel@xxxxxxxxxxxxxxxxxxx; Dan
> Magenheimer; Mauro; Olivier Hanesse; Jan Beulich; Xen Users; Mark Adams
> Subject: Re: [Xen-devel] [Xen-users] Re: Xen 4 TSC problems
> 
> On Wed, 2012-10-17 at 17:15 +0100, Keir Fraser wrote:
> > @@ -540,6 +541,14 @@ static void plt_overflow(void *unused)
> >          plt_wrap = __read_platform_stime(plt_stamp64 + plt_mask + 1);
> >          if ( ABS(plt_wrap - now) > ABS(plt_now - now) )
> >              break;
> > +        rdtscll(tsc);
> > +        printk("XXX plt_overflow: plt_now=%"PRIx64" plt_wrap=%"PRIx64
> > +               " now=%"PRIx64" old_stamp=%"PRIx64" new_stamp=%"PRIx64
> > +               " plt_stamp64=%"PRIx64" plt_mask=%"PRIx64
> > +               " tsc=%"PRIx64" tsc_stamp=%"PRIx64"\n",
> > +               plt_now, plt_wrap, now, old_stamp, plt_stamp, plt_stamp64,
> > +               plt_mask, tsc, this_cpu(cpu_time).local_tsc_stamp);
> > +        break;
> 
> Is the break here, making the following update to plt_stamp64 dead code
> deliberate?
> 
> >          plt_stamp64 += plt_mask + 1;
> >      }
> >      if ( i != 0 )
> 
> Ian.
> 
> 
> 
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