Re: [Xen-devel] [PATCH v2 4/6] x86: bring up all CPUs even if not all are supposed to be used

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 18.07.18 at 15:56, <wei.liu2@xxxxxxxxxx> wrote:
> On Wed, Jul 18, 2018 at 02:21:53AM -0600, Jan Beulich wrote:
>> --- a/xen/arch/x86/mpparse.c
>> +++ b/xen/arch/x86/mpparse.c
>> @@ -68,19 +68,26 @@ physid_mask_t phys_cpu_present_map;
>>  
>>  void __init set_nr_cpu_ids(unsigned int max_cpus)
>>  {
>> +    unsigned int tot_cpus = num_processors + disabled_cpus;
>> +
>>      if (!max_cpus)
>> -            max_cpus = num_processors + disabled_cpus;
>> +            max_cpus = tot_cpus;
>>      if (max_cpus > NR_CPUS)
>>              max_cpus = NR_CPUS;
>>      else if (!max_cpus)
>>              max_cpus = 1;
>>      printk(XENLOG_INFO "SMP: Allowing %u CPUs (%d hotplug CPUs)\n",
>>             max_cpus, max_t(int, max_cpus - num_processors, 0));
>> -    nr_cpu_ids = max_cpus;
>> +
>> +    if (!park_offline_cpus)
>> +            tot_cpus = max_cpus;
>> +    nr_cpu_ids = min(tot_cpus, NR_CPUS + 0u);
>> +    if (park_offline_cpus && nr_cpu_ids < num_processors)
>> +            printk(XENLOG_WARNING "SMP: Cannot bring up %u further CPUs\n",
>> +                   num_processors - nr_cpu_ids);
> 
> Minor nit:
> 
> Maybe it is just me, but "Cannot" is normally used when an operation
> fails, I would use "Won't" to indicate this is a deliberate action, not
> a consequence of failure, or say "Skip bringing up ...".

But it isn't a deliberate action - we just don't have enough bits to
represent all of them. To me this is the indication of a failure, just
that we catch it before it could actually cause problems.

> Whatever this log message ends up like:
> 
> Reviewed-by: Wei Liu <wei.liu2@xxxxxxxxxx>

Thanks.

Jan



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel