Re: [PATCH 1/6] perf/x86/rapl: Fix the energy-pkg event for AMD CPUs

[Dhananjay Ugwekar <Dhananjay.Ugwekar@amd.com>]

Hello Rui,

On 6/11/2024 11:05 AM, Zhang, Rui wrote:
> On Mon, 2024-06-10 at 10:07 +0000, Dhananjay Ugwekar wrote:
>> After commit ("x86/cpu/topology: Add support for the AMD 0x80000026
>> leaf"),
>> on AMD processors that support extended CPUID leaf 0x80000026, the
>> topology_die_cpumask() and topology_logical_die_id() macros, no
>> longer
>> return the package cpumask and package id, instead they return the
>> CCD
>> (Core Complex Die) mask and id respectively. This leads to the
>> energy-pkg
>> event scope to be modified to CCD instead of package.
>>
>> Replacing these macros with their package counterparts fixes the
>> energy-pkg event for AMD CPUs.
>>
>> However due to the difference between the scope of energy-pkg event
>> for
>> Intel and AMD CPUs,
> 
> Actually, on Intel platforms, the energy-pkg event is also package
> scope except one platform, and that one is the only multi-die system
> with RAPL MSRs available.
> So that is why the die/pkg logic was introduced in the first place.
> 
> I like the macro/helpers in this patch. The logic inside them may need
> to be optimized for Intel platforms, but that is a separate task.

Yes that is correct, however anyway the die macros return the package 
values on a single die system, so I preferred to use them for all Intel 
systems (single or multi-die). 

We can surely update the macro name or logic in future to make it more 
semantically correct.

Thanks for the review!

Regards,
Dhananjay

> 
>>  we have to replace these macros conditionally only for
>> AMD CPUs.
>>
>> On a 12 CCD 1 Package AMD Zen4 Genoa machine:
>>
>> Before:
>> $ cat /sys/devices/power/cpumask
>> 0,8,16,24,32,40,48,56,64,72,80,88.
>>
>> The expected cpumask here is supposed to be just "0", as it is a
>> package
>> scope event, only one CPU will be collecting the event for all the
>> CPUs in
>> the package.
>>
>> After:
>> $ cat /sys/devices/power/cpumask
>> 0
>>
>> Signed-off-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@amd.com>
>> Fixes: 63edbaa48a57 ("x86/cpu/topology: Add support for the AMD
>> 0x80000026 leaf")
> 
> Reviewed-by: Zhang Rui <rui.zhang@intel.com>
> 
> thanks,
> rui
>> ---
>> PS: This patch was earlier sent separately(link below), it has not
>> been 
>> merged yet, it is necessary for this patchset to work properly, also
>> it 
>> fixes the pre-existing energy-pkg event.
>> https://lore.kernel.org/linux-perf-users/20240502095115.177713-1-Dhananjay.Ugwekar@amd.com/
>> ---
>>  arch/x86/events/rapl.c | 30 ++++++++++++++++++++++++++----
>>  1 file changed, 26 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/x86/events/rapl.c b/arch/x86/events/rapl.c
>> index b985ca79cf97..73be25e1f4b4 100644
>> --- a/arch/x86/events/rapl.c
>> +++ b/arch/x86/events/rapl.c
>> @@ -103,6 +103,10 @@ static struct perf_pmu_events_attr
>> event_attr_##v = {                              \
>>         .event_str      =
>> str,                                                  \
>>  };
>>  
>> +#define rapl_pmu_is_pkg_scope()                                \
>> +       (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||  \
>> +        boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
>> +
>>  struct rapl_pmu {
>>         raw_spinlock_t          lock;
>>         int                     n_active;
>> @@ -140,9 +144,21 @@ static unsigned int rapl_cntr_mask;
>>  static u64 rapl_timer_ms;
>>  static struct perf_msr *rapl_msrs;
>>  
>> +static inline unsigned int get_rapl_pmu_idx(int cpu)
>> +{
>> +       return rapl_pmu_is_pkg_scope() ?
>> topology_logical_package_id(cpu) :
>> +                                       
>> topology_logical_die_id(cpu);
>> +}
>> +
>> +static inline const struct cpumask *get_rapl_pmu_cpumask(int cpu)
>> +{
>> +       return rapl_pmu_is_pkg_scope() ? topology_core_cpumask(cpu) :
>> +                                        topology_die_cpumask(cpu);
>> +}
>> +
>>  static inline struct rapl_pmu *cpu_to_rapl_pmu(unsigned int cpu)
>>  {
>> -       unsigned int rapl_pmu_idx = topology_logical_die_id(cpu);
>> +       unsigned int rapl_pmu_idx = get_rapl_pmu_idx(cpu);
>>  
>>         /*
>>          * The unsigned check also catches the '-1' return value for
>> non
>> @@ -543,6 +559,7 @@ static struct perf_msr amd_rapl_msrs[] = {
>>  
>>  static int rapl_cpu_offline(unsigned int cpu)
>>  {
>> +       const struct cpumask *rapl_pmu_cpumask =
>> get_rapl_pmu_cpumask(cpu);
>>         struct rapl_pmu *pmu = cpu_to_rapl_pmu(cpu);
>>         int target;
>>  
>> @@ -552,7 +569,7 @@ static int rapl_cpu_offline(unsigned int cpu)
>>  
>>         pmu->cpu = -1;
>>         /* Find a new cpu to collect rapl events */
>> -       target = cpumask_any_but(topology_die_cpumask(cpu), cpu);
>> +       target = cpumask_any_but(rapl_pmu_cpumask, cpu);
>>  
>>         /* Migrate rapl events to the new target */
>>         if (target < nr_cpu_ids) {
>> @@ -565,6 +582,8 @@ static int rapl_cpu_offline(unsigned int cpu)
>>  
>>  static int rapl_cpu_online(unsigned int cpu)
>>  {
>> +       unsigned int rapl_pmu_idx = get_rapl_pmu_idx(cpu);
>> +       const struct cpumask *rapl_pmu_cpumask =
>> get_rapl_pmu_cpumask(cpu);
>>         struct rapl_pmu *pmu = cpu_to_rapl_pmu(cpu);
>>         int target;
>>  
>> @@ -579,14 +598,14 @@ static int rapl_cpu_online(unsigned int cpu)
>>                 pmu->timer_interval = ms_to_ktime(rapl_timer_ms);
>>                 rapl_hrtimer_init(pmu);
>>  
>> -               rapl_pmus->pmus[topology_logical_die_id(cpu)] = pmu;
>> +               rapl_pmus->pmus[rapl_pmu_idx] = pmu;
>>         }
>>  
>>         /*
>>          * Check if there is an online cpu in the package which
>> collects rapl
>>          * events already.
>>          */
>> -       target = cpumask_any_and(&rapl_cpu_mask,
>> topology_die_cpumask(cpu));
>> +       target = cpumask_any_and(&rapl_cpu_mask, rapl_pmu_cpumask);
>>         if (target < nr_cpu_ids)
>>                 return 0;
>>  
>> @@ -677,6 +696,9 @@ static int __init init_rapl_pmus(void)
>>  {
>>         int nr_rapl_pmu = topology_max_packages() *
>> topology_max_dies_per_package();
>>  
>> +       if (rapl_pmu_is_pkg_scope())
>> +               nr_rapl_pmu = topology_max_packages();
>> +
>>         rapl_pmus = kzalloc(struct_size(rapl_pmus, pmus,
>> nr_rapl_pmu), GFP_KERNEL);
>>         if (!rapl_pmus)
>>                 return -ENOMEM;
>