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perf/x86/rapl: fix AMD event handling

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The RAPL events exposed under /sys/devices/power/events should only reflect
what the underlying hardware actually support. This is how it works on Intel
RAPL and Intel core/uncore PMUs in general.
But on AMD, this was not the case. All possible RAPL events were advertised.

This is what it showed on an AMD Fam17h:
$ ls /sys/devices/power/events/
energy-cores        energy-gpu          energy-pkg          energy-psys
energy-ram          energy-cores.scale  energy-gpu.scale    energy-pkg.scale
energy-psys.scale   energy-ram.scale    energy-cores.unit   energy-gpu.unit
energy-pkg.unit     energy-psys.unit    energy-ram.unit

Yet, on AMD Fam17h, only energy-pkg is supported.

This patch fixes the problem. Given the way perf_msr_probe() works, the
amd_rapl_msrs[] table has to have all entries filled out and in particular
the group field, otherwise perf_msr_probe() defaults to making the event
visible.

With the patch applied, the kernel now only shows was is actually supported:

$ ls /sys/devices/power/events/
energy-pkg  energy-pkg.scale  energy-pkg.unit

The patch also uses the RAPL_MSR_MASK because only the 32-bits LSB of the
RAPL counters are relevant when reading power consumption.

Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220105185659.643355-1-eranian@google.com
This commit is contained in:
Stephane Eranian 2022-01-05 10:56:59 -08:00 committed by Peter Zijlstra
parent 96fd2e89fb
commit 0036fb00a7
1 changed files with 6 additions and 3 deletions
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9
arch/x86/events/rapl.c
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@ -536,11 +536,14 @@ static struct perf_msr intel_rapl_spr_msrs[] = {
* - perf_msr_probe(PERF_RAPL_MAX)
* - want to use same event codes across both architectures
*/
static struct perf_msr amd_rapl_msrs[PERF_RAPL_MAX] = {
[PERF_RAPL_PKG] = { MSR_AMD_PKG_ENERGY_STATUS, &rapl_events_pkg_group, test_msr },
static struct perf_msr amd_rapl_msrs[] = {
[PERF_RAPL_PP0] = { 0, &rapl_events_cores_group, 0, false, 0 },
[PERF_RAPL_PKG] = { MSR_AMD_PKG_ENERGY_STATUS, &rapl_events_pkg_group, test_msr, false, RAPL_MSR_MASK },
[PERF_RAPL_RAM] = { 0, &rapl_events_ram_group, 0, false, 0 },
[PERF_RAPL_PP1] = { 0, &rapl_events_gpu_group, 0, false, 0 },
[PERF_RAPL_PSYS] = { 0, &rapl_events_psys_group, 0, false, 0 },
};
static int rapl_cpu_offline(unsigned int cpu)
{
struct rapl_pmu *pmu = cpu_to_rapl_pmu(cpu);