Re: [PATCH v3 6/9] cpu/SMT: Allow enabling partial SMT states via sysfs

[Laurent Dufour <ldufour@linux.ibm.com>]

Le 05/07/2023 à 05:14, Zhang, Rui a écrit :
> On Thu, 2023-06-29 at 16:31 +0200, Laurent Dufour wrote:
>> @@ -2580,6 +2597,17 @@ static ssize_t control_show(struct device
>> *dev,
>>   {
>>          const char *state = smt_states[cpu_smt_control];
>>   
>> +#ifdef CONFIG_HOTPLUG_SMT
>> +       /*
>> +        * If SMT is enabled but not all threads are enabled then
>> show the
>> +        * number of threads. If all threads are enabled show "on".
>> Otherwise
>> +        * show the state name.
>> +        */
>> +       if (cpu_smt_control == CPU_SMT_ENABLED &&
>> +           cpu_smt_num_threads != cpu_smt_max_threads)
>> +               return sysfs_emit(buf, "%d\n", cpu_smt_num_threads);
>> +#endif
>> +
> 
> My understanding is that cpu_smt_control is always set to
> CPU_SMT_NOT_IMPLEMENTED when CONFIG_HOTPLUG_SMT is not set, so this
> ifdef is not necessary, right?

Hi Rui,

Indeed, cpu_smt_control, cpu_smt_num_threads and cpu_smt_max_threads are 
only defined when CONFIG_HOTPLUG_SMT is set. This is the reason for this 
#ifdef block.

This has been reported by the kernel test robot testing v2:
https://lore.kernel.org/oe-kbuild-all/202306282340.Ihqm0fLA-lkp@intel.com

Cheers,
Laurent.