Re: [Powerpc-utils-devel] [PATCH] Fix ppc64_cpu --threads-per-core when --smt value set

[Paul C. <pc...@us...>]

On 01/07/2015 11:41 PM, Mamatha Inamdar wrote:
>
> On 01/08/2015 01:33 AM, Nathan Fontenot wrote:
>> On 01/07/2015 01:01 AM, Vasant Hegde wrote:
>>> On 12/23/2014 12:08 PM, Mamatha Inamdar wrote:
>>>> Problem: ppc64_cpu --threads-per-core gives wrong data when --smt value set
>>>>
>>>> This patch will resolve the above issue and display the correct values of threads-per-core
>>>> for the ppc64_cpu command when --smt value is set.
>>>>
>>>> I have used the following equation to calculate threads_per_core as per lscpu command.
>>>>
>>>> 	threads_per_core = nthreads / ncores
>> I think there may be a slight misunderstanding between the threads-per-core
>> option for the ppc64_cou command and what lscpu reports.
>>
>> The threads-per-core option to the ppc64_cpu command reports the number of
>> threads that a core contains, not the number of online threads per core.
>>
>> If you want to know the number of online threads per core you need to use the
>> --info or --smt option.
>>
>> -Nathan
>
> You mean threads-per-core option to the ppc64_cpu is working as expected.
>
> If yes then
>
> 1) Test team has to change there test case because they are comparing
>        results with "ppc64_cpu  --threads-per-core" with "lscpu
> threads(s) per core".
>
> Case 2: FAIL
> [root@lop826 ~]# ppc64_cpu --smt=4
> [root@lop826 ~]# ppc64_cpu --threads-per-core
> Threads per core: 8
>
> Verify with "lscpu" output:
> Thread(s) per core: 4
>
> 2) Can we change option name for ppc64_cpu..
> because  "--threads-per-core" and  "threads(s) per core" both are same
> but gives different results

I agree that there is confusion in the varied use of that phrase. 
Instead of changing ppc64_cpu, however, I would lean toward changing 
lscpu to report "SMT mode" instead.  It's much more likely that there 
are dependencies on the current usage of ppc64_cpu (including lscpu) 
than any dependencies on the output of lscpu.

Regards,
PC