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

[Vasant H. <heg...@li...>]

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
>
> ***********************************************
> Test results:
>
> CASE 1:
>
> ./src/ppc64_cpu --smt=on
> [root@llmjuno03b powerpc-utils]# ./src/ppc64_cpu --threads-per-core
> Threads per core: 4
>
> lscpu output:
> Thread(s) per core:    4
> ------------------------------------------
> CASE 2:
>
> ./src/ppc64_cpu --smt=2
> [root@llmjuno03b powerpc-utils]# ./src/ppc64_cpu --threads-per-core
> Threads per core: 2
>
> lscpu output:
> Thread(s) per core:    2
> --------------------------------------------------
> CASE 3:
>
> ./src/ppc64_cpu --smt=1
> [root@llmjuno03b powerpc-utils]# ./src/ppc64_cpu --threads-per-core
> Threads per core: 1
>
> lscpu output:
> Thread(s) per core:    1
> -------------------------------------------------
>
> Signed-off-by: Mamatha Inamdar <mam...@li...>
> ---
>   src/ppc64_cpu.c |   15 ++++++++++++++-
>   1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/src/ppc64_cpu.c b/src/ppc64_cpu.c
> index 4df4cdc..a3cfed0 100644
> --- a/src/ppc64_cpu.c
> +++ b/src/ppc64_cpu.c
> @@ -56,6 +56,7 @@ static int counters[MAX_NR_CPUS];
>   static int threads_per_cpu = 0;
>   static int cpus_in_system = 0;
>   static int threads_in_system = 0;
> +static int threads_per_core = 0;

Why do you need another global variable ? can't you just print " nthreads / 
cpus_in_system" ?

>
>   static int do_info(void);
>
> @@ -529,9 +530,21 @@ static int do_smt(char *state)
>   	return rc;
>   }
>
> +/* Threads per core */
>   static inline void do_threads_per_core()
>   {
> -	printf("Threads per core: %d\n", threads_per_cpu);
> +	int i, j;
> +	int nthreads;    /* number of threads online */

initialize nthreads ?


> +
> +	/* Calculate number of threads present on the system */
> +	for (j = 0; j < threads_in_system; j += threads_per_cpu) {
> +		for (i = 0; i < threads_per_cpu; i++)
> +			nthreads += cpu_online(j + i);
> +	}

Can we have different cores with different SMT level?

-Vasant

> +
> +	/* Calculate threads per core = nthreads / ncores */
> +	threads_per_core = nthreads / cpus_in_system;
> +	printf("Threads per core: %d\n", threads_per_core);
>   }
>
>   static int do_subcores_per_core(char *state)
>
>
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