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Date:   Fri, 1 Mar 2019 11:59:40 -0500
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Jiri Olsa <jolsa@...hat.com>, Peter Zijlstra <peterz@...radead.org>
Cc:     Vince Weaver <vincent.weaver@...ne.edu>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        lkml <linux-kernel@...r.kernel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Stephane Eranian <eranian@...gle.com>
Subject: Re: [RFC] perf/x86/rapl: Getting zero on energy-cores event



On 3/1/2019 6:42 AM, Jiri Olsa wrote:
> hi,
> I'm getting zero counts for energy-cores event on broadwell-x
> server (model 0x4f)
> 
> I checked intel_rapl powercap driver and it won't export the
> counter if it rdmsr returns zero on it
> 
> the SDM also says the rdmsr returns zero for some models
> 
> I made changes on perf rapl pmu below to remove sysfs events
> if their rdmsr returns zero just to ilustrate the case
> 
> I think there's probably better fix, but I'm not sure if
> there's a reason for zero counters to be exposed..?

+Stephane, who is the author.

I'm OK to hide the zero counters.


> 
> thoughts? thanks,
> jirka
> 
> 
> ---
> diff --git a/arch/x86/events/intel/rapl.c b/arch/x86/events/intel/rapl.c
> index 94dc564146ca..effb9a9d2368 100644
> --- a/arch/x86/events/intel/rapl.c
> +++ b/arch/x86/events/intel/rapl.c
> @@ -54,6 +54,7 @@
>   #include <linux/module.h>
>   #include <linux/slab.h>
>   #include <linux/perf_event.h>
> +#include <linux/nospec.h>
>   #include <asm/cpu_device_id.h>
>   #include <asm/intel-family.h>
>   #include "../perf_event.h"
> @@ -346,10 +347,18 @@ static void rapl_pmu_event_del(struct perf_event *event, int flags)
>   	rapl_pmu_event_stop(event, PERF_EF_UPDATE);
>   }
>   
> +static unsigned int event_msr[NR_RAPL_DOMAINS] = {
> +	MSR_PP0_ENERGY_STATUS,
> +	MSR_PKG_ENERGY_STATUS,
> +	MSR_DRAM_ENERGY_STATUS,
> +	MSR_PP1_ENERGY_STATUS,
> +	MSR_PLATFORM_ENERGY_STATUS,
> +};
> +
>   static int rapl_pmu_event_init(struct perf_event *event)
>   {
>   	u64 cfg = event->attr.config & RAPL_EVENT_MASK;
> -	int bit, msr, ret = 0;
> +	int bit, ret = 0;
>   	struct rapl_pmu *pmu;
>   
>   	/* only look at RAPL events */
> @@ -365,33 +374,12 @@ static int rapl_pmu_event_init(struct perf_event *event)
>   
>   	event->event_caps |= PERF_EV_CAP_READ_ACTIVE_PKG;
>   
> -	/*
> -	 * check event is known (determines counter)
> -	 */
> -	switch (cfg) {
> -	case INTEL_RAPL_PP0:
> -		bit = RAPL_IDX_PP0_NRG_STAT;
> -		msr = MSR_PP0_ENERGY_STATUS;
> -		break;
> -	case INTEL_RAPL_PKG:
> -		bit = RAPL_IDX_PKG_NRG_STAT;
> -		msr = MSR_PKG_ENERGY_STATUS;
> -		break;
> -	case INTEL_RAPL_RAM:
> -		bit = RAPL_IDX_RAM_NRG_STAT;
> -		msr = MSR_DRAM_ENERGY_STATUS;
> -		break;
> -	case INTEL_RAPL_PP1:
> -		bit = RAPL_IDX_PP1_NRG_STAT;
> -		msr = MSR_PP1_ENERGY_STATUS;
> -		break;
> -	case INTEL_RAPL_PSYS:
> -		bit = RAPL_IDX_PSYS_NRG_STAT;
> -		msr = MSR_PLATFORM_ENERGY_STATUS;
> -		break;
> -	default:
> +	if (!cfg || cfg >= NR_RAPL_DOMAINS)
>   		return -EINVAL;
> -	}
> +
> +	cfg = array_index_nospec(cfg, NR_RAPL_DOMAINS);
> +	bit = cfg - 1;
> +
>   	/* check event supported */
>   	if (!(rapl_cntr_mask & (1 << bit)))
>   		return -EINVAL;
> @@ -406,7 +394,7 @@ static int rapl_pmu_event_init(struct perf_event *event)
>   		return -EINVAL;
>   	event->cpu = pmu->cpu;
>   	event->pmu_private = pmu;
> -	event->hw.event_base = msr;
> +	event->hw.event_base = event_msr[bit];
>   	event->hw.config = cfg;
>   	event->hw.idx = bit;
>   
> @@ -435,11 +423,27 @@ static struct attribute_group rapl_pmu_attr_group = {
>   	.attrs = rapl_pmu_attrs,
>   };
>   
> -RAPL_EVENT_ATTR_STR(energy-cores, rapl_cores, "event=0x01");
> -RAPL_EVENT_ATTR_STR(energy-pkg  ,   rapl_pkg, "event=0x02");
> -RAPL_EVENT_ATTR_STR(energy-ram  ,   rapl_ram, "event=0x03");
> -RAPL_EVENT_ATTR_STR(energy-gpu  ,   rapl_gpu, "event=0x04");
> -RAPL_EVENT_ATTR_STR(energy-psys,   rapl_psys, "event=0x05");
> +static ssize_t
> +rapl_event_sysfs_show(struct device *dev, struct device_attribute *attr,
> +		      char *page)
> +{
> +	struct perf_pmu_events_attr *pmu_attr =
> +		container_of(attr, struct perf_pmu_events_attr, attr);
> +
> +	return sprintf(page, "event=%llu\n", pmu_attr->id);
> +}
> +
> +#define RAPL_EVENT_ATTR(_name, v, _id)					\
> +static struct perf_pmu_events_attr event_attr_##v = {			\
> +	.attr	= __ATTR(_name, 0444, rapl_event_sysfs_show, NULL),	\
> +	.id	= RAPL_IDX_##_id##_NRG_STAT,				\
> +};
> +
> +RAPL_EVENT_ATTR(energy-cores,  rapl_cores,  PP0);
> +RAPL_EVENT_ATTR(energy-pkg  ,    rapl_pkg,  PKG);
> +RAPL_EVENT_ATTR(energy-ram  ,    rapl_ram,  RAM);
> +RAPL_EVENT_ATTR(energy-gpu  ,    rapl_gpu,  PP1);
> +RAPL_EVENT_ATTR(energy-psys ,   rapl_psys, PSYS);
>   
>   RAPL_EVENT_ATTR_STR(energy-cores.unit, rapl_cores_unit, "Joules");
>   RAPL_EVENT_ATTR_STR(energy-pkg.unit  ,   rapl_pkg_unit, "Joules");
> @@ -780,6 +784,59 @@ static const struct x86_cpu_id rapl_cpu_match[] __initconst = {
>   
>   MODULE_DEVICE_TABLE(x86cpu, rapl_cpu_match);
>   
> +static void __init remove_name(struct attribute **attrs, const char *name)
> +{
> +	struct device_attribute *attr;
> +	int i, j;
> +
> +	for (i = 0; attrs[i]; i++) {
> +		attr = (struct device_attribute *) attrs[i];
> +
> +		if (strncmp(name, attr->attr.name, strlen(name)))
> +			continue;
> +
> +		for (j = i; attrs[j]; j++)
> +			attrs[j] = attrs[j + 1];
> +
> +		/* Check the shifted attr. */
> +		i--;
> +	}
> +}
> +
> +static void __init check_events(struct attribute **attrs)
> +{
> +	struct perf_pmu_events_attr *pmu_attr;
> +	struct device_attribute *attr;
> +	int i, j;
> +
> +	for (i = 0; attrs[i]; i++) {
> +		u64 val = 0;
> +		u64 bit;
> +
> +		attr     = (struct device_attribute *) attrs[i];
> +		pmu_attr = container_of(attr, struct perf_pmu_events_attr, attr);
> +
> +		if (pmu_attr->event_str)
> +			continue;
> +
> +		bit = pmu_attr->id;
> +
> +		if (WARN_ON_ONCE(bit >= NR_RAPL_DOMAINS))
> +			continue;
> +
> +		if (!rdmsrl_safe(event_msr[bit], &val) && val)
> +			continue;
> +
> +		remove_name(&attrs[i + 1], attr->attr.name);

In perf cstate, we check and insert the available events for sysfs attrs
I think we should use the same way here. It's better to factor out a 
common function for both cstate and rapl.


Peter,

The cstate, rapl and uncore are similar. I think it should be the right 
direction to abstract several common functions for them.
Here, the sysfs attrs is an example.
The common topology related functions I proposed is another example.
https://lore.kernel.org/lkml/9631a92f-5b24-26a6-e160-4e4c0b4697c1@linux.intel.com/

Thanks,
Kan

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