Re: [dpdk-stable] [PATCH] power: fix current frequency index

["Liang, Ma" <liang.j.ma@intel.com>]

Hi Reshma, 

   I'm OK with the change. That's the missing part about init process.

Reviewed-by Liang Ma <liang.j.ma@intel.com>

Regards
Liang

On 29 Jul 14:58, Reshma Pattan wrote:
> 1)
> During power initialization the pstate cpufreq api is
> not setting the initial curr_idx of pstate_power_info
> to corresponding current frequency index.
> 
> Without this the idx is always 0, which is causing the
> below check to pass and returns without setting the initial
> min/max frequency to system max frequency and this leads to
> incorrect frequency settings when power_pstate_cpufreq_set_freq()
> is called in the apps.
> 
> set_freq_internal(struct pstate_power_info *pi, uint32_t idx)
> {
> ...
> 
>  /* Check if it is the same as current */
>         if (idx == pi->curr_idx)
>                 return 0;
> ...
> }
> 
> scenario 1:
> If system has starting scaling min/max: 1000/1000, and want to
> set this to 2200/2200, the max frequency gets updated but not min.
> 
> scenario 2:
> If system has starting scaling min/max: 2200/1000, and want to set
> to 2200/2200, the max, min frequency was not updated. Since no change
> in max that should be ok, but min was also ignored, which will be fixed
> now with the new changes.
> 
> Fixes: e6c6dc0f ("power: add p-state driver compatibility")
> Cc: stable@dpdk.org
> CC: liang.j.ma@intel.com
> Signed-off-by: Reshma Pattan <reshma.pattan@intel.com>
> ---
>  lib/librte_power/power_pstate_cpufreq.c | 59 +++++++++++++++++++++++++++++++++
>  1 file changed, 59 insertions(+)
> 
> diff --git a/lib/librte_power/power_pstate_cpufreq.c b/lib/librte_power/power_pstate_cpufreq.c
> index 2526441..262f024 100644
> --- a/lib/librte_power/power_pstate_cpufreq.c
> +++ b/lib/librte_power/power_pstate_cpufreq.c
> @@ -52,6 +52,9 @@
>  		} \
>  } while (0)
>  
> +/* macros used for rounding frequency to nearest 100000 */
> +#define FREQ_ROUNDING_DELTA 50000
> +#define ROUND_FREQ_TO_N_100000 100000
>  
>  #define POWER_CONVERT_TO_DECIMAL 10
>  #define BUS_FREQ     100000
> @@ -532,6 +535,57 @@ struct pstate_power_info {
>  	return ret;
>  }
>  
> +static int
> +power_get_cur_idx(struct pstate_power_info *pi)
> +{
> +	FILE *f_cur;
> +	int ret = -1;
> +	char *p_cur;
> +	char buf_cur[BUFSIZ];
> +	char fullpath_cur[PATH_MAX];
> +	char *s_cur;
> +	uint32_t sys_cur_freq = 0;
> +	unsigned int i;
> +
> +	snprintf(fullpath_cur, sizeof(fullpath_cur),
> +			POWER_SYSFILE_CUR_FREQ,
> +			pi->lcore_id);
> +	f_cur = fopen(fullpath_cur, "r");
> +	FOPEN_OR_ERR_RET(f_cur, ret);
> +
> +	/* initialize the cur_idx to matching current frequency freq index */
> +	s_cur = fgets(buf_cur, sizeof(buf_cur), f_cur);
> +	FOPS_OR_NULL_GOTO(s_cur, fail);
> +
> +	p_cur = strchr(buf_cur, '\n');
> +	if (p_cur != NULL)
> +		*p_cur = 0;
> +	sys_cur_freq = strtoul(buf_cur, &p_cur, POWER_CONVERT_TO_DECIMAL);
> +
> +	/* convert the frequency to nearest 100000 value
> +	 * Ex: if sys_cur_freq=1396789 then freq_conv=1400000
> +	 * Ex: if sys_cur_freq=800030 then freq_conv=800000
> +	 * Ex: if sys_cur_freq=800030 then freq_conv=800000
> +	 */
> +	unsigned int freq_conv = 0;
> +	freq_conv = (sys_cur_freq + FREQ_ROUNDING_DELTA)
> +				/ ROUND_FREQ_TO_N_100000;
> +	freq_conv = freq_conv * ROUND_FREQ_TO_N_100000;
> +
> +	for (i = 0; i < pi->nb_freqs; i++) {
> +		if (freq_conv == pi->freqs[i]) {
> +			pi->curr_idx = i;
> +			break;
> +		}
> +	}
> +
> +	fclose(f_cur);
> +	return 0;
> +fail:
> +	fclose(f_cur);
> +	return ret;
> +}
> +
>  int
>  power_pstate_cpufreq_check_supported(void)
>  {
> @@ -578,6 +632,11 @@ struct pstate_power_info {
>  		goto fail;
>  	}
>  
> +	if (power_get_cur_idx(pi) < 0) {
> +		RTE_LOG(ERR, POWER, "Cannot get current frequency "
> +				"index of lcore %u\n", lcore_id);
> +		goto fail;
> +	}
>  
>  	/* Set freq to max by default */
>  	if (power_pstate_cpufreq_freq_max(lcore_id) < 0) {
> -- 
> 1.8.3.1
>