linux-kernel - RE: [PATCH v2 1/4] powercap/rapl: further relax energy counter checks

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Date:	Wed, 30 Apr 2014 05:29:54 +0000
From:	"R, Durgadoss" <durgadoss.r@...el.com>
To:	"David E. Box" <david.e.box@...ux.intel.com>,
	"jacob.jun.pan@...ux.intel.com" <jacob.jun.pan@...ux.intel.com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"hpa@...ux.intel.com" <hpa@...ux.intel.com>
CC:	"alan@...ux.intel.com" <alan@...ux.intel.com>,
	"Accardi, Kristen C" <kristen.c.accardi@...el.com>
Subject: RE: [PATCH v2 1/4] powercap/rapl: further relax energy counter
 checks



> -----Original Message-----
> From: David E. Box [mailto:david.e.box@...ux.intel.com]
> Sent: Wednesday, April 30, 2014 4:03 AM
> To: david.e.box@...ux.intel.com; jacob.jun.pan@...ux.intel.com; linux-
> pm@...r.kernel.org; Wysocki, Rafael J; linux-kernel@...r.kernel.org;
> hpa@...ux.intel.com
> Cc: alan@...ux.intel.com; R, Durgadoss; Accardi, Kristen C
> Subject: [PATCH v2 1/4] powercap/rapl: further relax energy counter checks
> 
> From: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> 
> Energy counters may roll slowly for some RAPL domains, checking all
> of them can be time consuming and takes unpredictable amount of time.
> Therefore, we relax the sanity check by only checking availability of the
> MSRs and non-zero value of the energy status counters. It has been shown
> sufficient for all the platforms tested to filter out inactive domains.
> 

Acked-by: Durgadoss R <durgadoss.r@...el.com>

Thanks,
Durga

> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> ---
>  drivers/powercap/intel_rapl.c |   29 +++++++++--------------------
>  1 file changed, 9 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/powercap/intel_rapl.c b/drivers/powercap/intel_rapl.c
> index d9a0770..1c987d2 100644
> --- a/drivers/powercap/intel_rapl.c
> +++ b/drivers/powercap/intel_rapl.c
> @@ -1124,8 +1124,7 @@ err_cleanup_package:
>  static int rapl_check_domain(int cpu, int domain)
>  {
>  	unsigned msr;
> -	u64 val1, val2 = 0;
> -	int retry = 0;
> +	u64 val = 0;
> 
>  	switch (domain) {
>  	case RAPL_DOMAIN_PACKAGE:
> @@ -1144,26 +1143,13 @@ static int rapl_check_domain(int cpu, int domain)
>  		pr_err("invalid domain id %d\n", domain);
>  		return -EINVAL;
>  	}
> -	if (rdmsrl_safe_on_cpu(cpu, msr, &val1))
> -		return -ENODEV;
> -
> -	/* PP1/uncore/graphics domain may not be active at the time of
> -	 * driver loading. So skip further checks.
> +	/* make sure domain counters are available and contains non-zero
> +	 * values, otherwise skip it.
>  	 */
> -	if (domain == RAPL_DOMAIN_PP1)
> -		return 0;
> -	/* energy counters roll slowly on some domains */
> -	while (++retry < 10) {
> -		usleep_range(10000, 15000);
> -		rdmsrl_safe_on_cpu(cpu, msr, &val2);
> -		if ((val1 & ENERGY_STATUS_MASK) != (val2 &
> ENERGY_STATUS_MASK))
> -			return 0;
> -	}
> -	/* if energy counter does not change, report as bad domain */
> -	pr_info("domain %s energy ctr %llu:%llu not working, skip\n",
> -		rapl_domain_names[domain], val1, val2);
> +	if (rdmsrl_safe_on_cpu(cpu, msr, &val) || !val)
> +		return -ENODEV;
> 
> -	return -ENODEV;
> +	return 0;
>  }
> 
>  /* Detect active and valid domains for the given CPU, caller must
> @@ -1180,6 +1166,9 @@ static int rapl_detect_domains(struct rapl_package *rp,
> int cpu)
>  		/* use physical package id to read counters */
>  		if (!rapl_check_domain(cpu, i))
>  			rp->domain_map |= 1 << i;
> +		else
> +			pr_warn("RAPL domain %s detection failed\n",
> +				rapl_domain_names[i]);
>  	}
>  	rp->nr_domains = bitmap_weight(&rp->domain_map,
> 	RAPL_DOMAIN_MAX);
>  	if (!rp->nr_domains) {
> --
> 1.7.10.4

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