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

[Keir Fraser <keir.xen@xxxxxxxxx>]

On 18/10/2012 08:40, "Ian Campbell" <Ian.Campbell@xxxxxxxxxx> wrote:

> 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?

Yes, it's a hack to disable the timer-has-apparently-wrapped workaround.

 -- Keir

>>          plt_stamp64 += plt_mask + 1;
>>      }
>>      if ( i != 0 )
> 
> Ian.
> 
> 



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