linux-kernel - Re: [PATCH v5 3/3] perf x86: Exposing an Uncore unit to PMON for Intel Xeon® server platform

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Message-ID: <7a697574-aa76-3eda-d504-1ec72bcb6353@linux.intel.com>
Date:   Wed, 12 Feb 2020 20:31:02 +0300
From:   "Sudarikov, Roman" <roman.sudarikov@...ux.intel.com>
To:     Greg KH <gregkh@...uxfoundation.org>,
        "Liang, Kan" <kan.liang@...ux.intel.com>
Cc:     Andi Kleen <ak@...ux.intel.com>, peterz@...radead.org,
        mingo@...hat.com, acme@...nel.org, mark.rutland@....com,
        alexander.shishkin@...ux.intel.com, jolsa@...hat.com,
        namhyung@...nel.org, linux-kernel@...r.kernel.org,
        eranian@...gle.com, bgregg@...flix.com, alexander.antonov@...el.com
Subject: Re: [PATCH v5 3/3] perf x86: Exposing an Uncore unit to PMON for Intel Xeon® server platform

On 11.02.2020 23:14, Greg KH wrote:
> On Tue, Feb 11, 2020 at 02:59:21PM -0500, Liang, Kan wrote:
>>
>> On 2/11/2020 1:57 PM, Greg KH wrote:
>>> On Tue, Feb 11, 2020 at 10:42:00AM -0800, Andi Kleen wrote:
>>>> On Tue, Feb 11, 2020 at 09:15:44AM -0800, Greg KH wrote:
>>>>> On Tue, Feb 11, 2020 at 07:15:49PM +0300, roman.sudarikov@...ux.intel.com wrote:
>>>>>> +static ssize_t skx_iio_mapping_show(struct device *dev,
>>>>>> +				struct device_attribute *attr, char *buf)
>>>>>> +{
>>>>>> +	struct pmu *pmu = dev_get_drvdata(dev);
>>>>>> +	struct intel_uncore_pmu *uncore_pmu =
>>>>>> +		container_of(pmu, struct intel_uncore_pmu, pmu);
>>>>>> +
>>>>>> +	struct dev_ext_attribute *ea =
>>>>>> +		container_of(attr, struct dev_ext_attribute, attr);
>>>>>> +	long die = (long)ea->var;
>>>>>> +
>>>>>> +	return sprintf(buf, "0000:%02x\n", skx_iio_stack(uncore_pmu, die));
>>>>> If "0000:" is always the "prefix" of the output of this file, why have
>>>>> it at all as you always know it is there?
>>
>> I think Roman only test with BIOS configured as single-segment. So he
>> hard-code the segment# here.
>>
>> I'm not sure if Roman can do some test with multiple-segment BIOS. If not, I
>> think we should at least print a warning here.
>>
>>>>> What is ever going to cause that to change?
>>>> I think it's just to make it a complete PCI address.
>>> Is that what this really is?  If so, it's not a "complete" pci address,
>>> is it?  If it is, use the real pci address please.
>> I think we don't need a complete PCI address here. The attr is to disclose
>> the mapping information between die and PCI BUS. Segment:BUS should be good
>> enough.
> "good enough" for today, but note that you can not change the format of
> the data in the file in the future, you would have to create a new file.
> So I suggest at least try to future-proof it as much as possible if you
> _know_ this could change.
>
> Just use the full pci address, there's no reason not to, otherwise it's
> just confusing.
>
> thanks,
>
> greg k-h
Hi Greg,

Yes, the "Segment:Bus" pair is enough to distinguish between different 
Root ports.
Please see the changes below which are to address all previous comments.

Thanks,
Roman

diff --git a/arch/x86/events/intel/uncore_snbep.c 
b/arch/x86/events/intel/uncore_snbep.c
index 96fca1ac22a4..f805fbdbbe81 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -3616,15 +3616,22 @@ skx_iio_mapping_visible(struct kobject *kobj, 
struct attribute *attr, int die)
  static ssize_t skx_iio_mapping_show(struct device *dev,
                  struct device_attribute *attr, char *buf)
  {
+    struct pci_bus *bus = NULL;
      struct pmu *pmu = dev_get_drvdata(dev);
      struct intel_uncore_pmu *uncore_pmu =
          container_of(pmu, struct intel_uncore_pmu, pmu);
+    int pmu_idx = uncore_pmu->pmu_idx;

      struct dev_ext_attribute *ea =
          container_of(attr, struct dev_ext_attribute, attr);
      long die = (long)ea->var;

-    return sprintf(buf, "0000:%02x\n", skx_iio_stack(uncore_pmu, die));
+    do {
+        bus = pci_find_next_bus(bus);
+    } while (pmu_idx--);
+
+    return sprintf(buf, "%04x:%02x\n", pci_domain_nr(bus),
+                       skx_iio_stack(uncore_pmu, die));
  }

  static int skx_msr_cpu_bus_read(int cpu, u64 *topology)
@@ -3691,10 +3698,7 @@ static int skx_iio_get_topology(struct 
intel_uncore_type *type)
      return 0;
  }

-static struct attribute *uncore_empry_attr;
-
  static struct attribute_group skx_iio_mapping_group = {
-    .attrs        = &uncore_empry_attr,
      .is_visible    = skx_iio_mapping_visible,
  };

@@ -3729,7 +3733,8 @@ static int skx_iio_set_mapping(struct 
intel_uncore_type *type)
          return -ENOMEM;
      }
      for (die = 0; die < uncore_max_dies(); die++) {
-        sprintf(buf, "node%ld", die);
+        sprintf(buf, "die%ld", die);
+        sysfs_attr_init(&eas[die].attr.attr);
          eas[die].attr.attr.name = kstrdup(buf, GFP_KERNEL);
          if (!eas[die].attr.attr.name) {
              ret = -ENOMEM;
@@ -3752,6 +3757,7 @@ static int skx_iio_set_mapping(struct 
intel_uncore_type *type)
      kfree(eas);
      kfree(attrs);
      kfree(type->topology);
+    type->attr_update = NULL;

      return ret;
  }