[PATCH v2] perf/rapl: support per domain energy unit

[Jacob Pan]

RAPL energy hardware unit can vary within a single CPU package, e.g.
HSW server DRAM has a fixed energy unit of 15.3 uJ (2^-16) whereas
the unit on other domains can be enumerated from power unit MSR.
There might be other variations in the future, this patch adds
per cpu model quirk to allow special handling of certain cpus.

hw_unit is also removed from per cpu data since it is not per cpu
and the sampling rate for energy counter is typically not high.

Without this patch, DRAM domain on HSW servers will be counted
4x higher than the real energy counter.

Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
---
 arch/x86/kernel/cpu/perf_event_intel_rapl.c | 91 ++++++++++++++++++++++-------
 1 file changed, 70 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_rapl.c b/arch/x86/kernel/cpu/perf_event_intel_rapl.c
index c4bb8b8..ead2ee9 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_rapl.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_rapl.c
@@ -62,6 +62,14 @@
 #define RAPL_IDX_PP1_NRG_STAT	3	/* gpu */
 #define INTEL_RAPL_PP1		0x4	/* pseudo-encoding */
 
+#define NR_RAPL_DOMAINS         0x4
+static const char *rapl_domain_names[NR_RAPL_DOMAINS] __initconst = {
+	"pp0-core",
+	"package",
+	"dram",
+	"pp1-gpu",
+};
+
 /* Clients have PP0, PKG */
 #define RAPL_IDX_CLN	(1<<RAPL_IDX_PP0_NRG_STAT|\
 			 1<<RAPL_IDX_PKG_NRG_STAT|\
@@ -112,7 +120,6 @@ static struct perf_pmu_events_attr event_attr_##v = {			\
 
 struct rapl_pmu {
 	spinlock_t	 lock;
-	int		 hw_unit;  /* 1/2^hw_unit Joule */
 	int		 n_active; /* number of active events */
 	struct list_head active_list;
 	struct pmu	 *pmu; /* pointer to rapl_pmu_class */
@@ -120,6 +127,7 @@ struct rapl_pmu {
 	struct hrtimer   hrtimer;
 };
 
+static int rapl_hw_unit[NR_RAPL_DOMAINS] __read_mostly;  /* 1/2^hw_unit Joule */
 static struct pmu rapl_pmu_class;
 static cpumask_t rapl_cpu_mask;
 static int rapl_cntr_mask;
@@ -127,6 +135,7 @@ static int rapl_cntr_mask;
 static DEFINE_PER_CPU(struct rapl_pmu *, rapl_pmu);
 static DEFINE_PER_CPU(struct rapl_pmu *, rapl_pmu_to_free);
 
+static struct x86_pmu_quirk *rapl_quirks;
 static inline u64 rapl_read_counter(struct perf_event *event)
 {
 	u64 raw;
@@ -134,15 +143,28 @@ static inline u64 rapl_read_counter(struct perf_event *event)
 	return raw;
 }
 
-static inline u64 rapl_scale(u64 v)
+#define rapl_add_quirk(func_)						\
+do {									\
+	static struct x86_pmu_quirk __quirk __initdata = {		\
+		.func = func_,						\
+	};								\
+	__quirk.next = rapl_quirks;					\
+	rapl_quirks = &__quirk;						\
+} while (0)
+
+static inline u64 rapl_scale(u64 v, int cfg)
 {
+	if (cfg > NR_RAPL_DOMAINS) {
+		pr_warn("invalid domain %d, failed to scale data\n", cfg);
+		return v;
+	}
 	/*
 	 * scale delta to smallest unit (1/2^32)
 	 * users must then scale back: count * 1/(1e9*2^32) to get Joules
 	 * or use ldexp(count, -32).
 	 * Watts = Joules/Time delta
 	 */
-	return v << (32 - __this_cpu_read(rapl_pmu)->hw_unit);
+	return v << (32 - rapl_hw_unit[cfg - 1]);
 }
 
 static u64 rapl_event_update(struct perf_event *event)
@@ -173,7 +195,7 @@ again:
 	delta = (new_raw_count << shift) - (prev_raw_count << shift);
 	delta >>= shift;
 
-	sdelta = rapl_scale(delta);
+	sdelta = rapl_scale(delta, event->hw.config);
 
 	local64_add(sdelta, &event->count);
 
@@ -546,12 +568,22 @@ static void rapl_cpu_init(int cpu)
 	cpumask_set_cpu(cpu, &rapl_cpu_mask);
 }
 
+static __init void rapl_hsw_server_quirk(void)
+{
+	/*
+	 * DRAM domain on HSW server has fixed energy unit which can be
+	 * different than the unit from power unit MSR.
+	 * "Intel Xeon Processor E5-1600 and E5-2600 v3 Product Families, V2
+	 * of 2. Datasheet, September 2014, Reference Number: 330784-001 "
+	 */
+	rapl_hw_unit[RAPL_IDX_RAM_NRG_STAT] = 16;
+}
+
 static int rapl_cpu_prepare(int cpu)
 {
 	struct rapl_pmu *pmu = per_cpu(rapl_pmu, cpu);
 	int phys_id = topology_physical_package_id(cpu);
 	u64 ms;
-	u64 msr_rapl_power_unit_bits;
 
 	if (pmu)
 		return 0;
@@ -559,24 +591,13 @@ static int rapl_cpu_prepare(int cpu)
 	if (phys_id < 0)
 		return -1;
 
-	/* protect rdmsrl() to handle virtualization */
-	if (rdmsrl_safe(MSR_RAPL_POWER_UNIT, &msr_rapl_power_unit_bits))
-		return -1;
-
 	pmu = kzalloc_node(sizeof(*pmu), GFP_KERNEL, cpu_to_node(cpu));
 	if (!pmu)
 		return -1;
-
 	spin_lock_init(&pmu->lock);
 
 	INIT_LIST_HEAD(&pmu->active_list);
 
-	/*
-	 * grab power unit as: 1/2^unit Joules
-	 *
-	 * we cache in local PMU instance
-	 */
-	pmu->hw_unit = (msr_rapl_power_unit_bits >> 8) & 0x1FULL;
 	pmu->pmu = &rapl_pmu_class;
 
 	/*
@@ -586,8 +607,8 @@ static int rapl_cpu_prepare(int cpu)
 	 * divide interval by 2 to avoid lockstep (2 * 100)
 	 * if hw unit is 32, then we use 2 ms 1/200/2
 	 */
-	if (pmu->hw_unit < 32)
-		ms = (1000 / (2 * 100)) * (1ULL << (32 - pmu->hw_unit - 1));
+	if (rapl_hw_unit[0] < 32)
+		ms = (1000 / (2 * 100)) * (1ULL << (32 - rapl_hw_unit[0] - 1));
 	else
 		ms = 2;
 
@@ -655,6 +676,20 @@ static int rapl_cpu_notifier(struct notifier_block *self,
 	return NOTIFY_OK;
 }
 
+static int rapl_check_hw_unit(void)
+{
+	u64 msr_rapl_power_unit_bits;
+	int i;
+
+	/* protect rdmsrl() to handle virtualization */
+	if (rdmsrl_safe(MSR_RAPL_POWER_UNIT, &msr_rapl_power_unit_bits))
+		return -1;
+	for (i = 0; i < NR_RAPL_DOMAINS; i++)
+		rapl_hw_unit[i] = (msr_rapl_power_unit_bits >> 8) & 0x1FULL;
+
+	return 0;
+}
+
 static const struct x86_cpu_id rapl_cpu_match[] = {
 	[0] = { .vendor = X86_VENDOR_INTEL, .family = 6 },
 	[1] = {},
@@ -664,6 +699,8 @@ static int __init rapl_pmu_init(void)
 {
 	struct rapl_pmu *pmu;
 	int cpu, ret;
+	struct x86_pmu_quirk *quirk;
+	int i;
 
 	/*
 	 * check for Intel processor family 6
@@ -678,6 +715,8 @@ static int __init rapl_pmu_init(void)
 		rapl_cntr_mask = RAPL_IDX_CLN;
 		rapl_pmu_events_group.attrs = rapl_events_cln_attr;
 		break;
+	case 63: /* Haswell-Server */
+		rapl_add_quirk(rapl_hsw_server_quirk);
 	case 60: /* Haswell */
 	case 69: /* Haswell-Celeron */
 		rapl_cntr_mask = RAPL_IDX_HSW;
@@ -693,7 +732,13 @@ static int __init rapl_pmu_init(void)
 		/* unsupported */
 		return 0;
 	}
+	ret = rapl_check_hw_unit();
+	if (ret)
+		return ret;
 
+	/* run cpu model quirks */
+	for (quirk = rapl_quirks; quirk; quirk = quirk->next)
+		quirk->func();
 	cpu_notifier_register_begin();
 
 	for_each_online_cpu(cpu) {
@@ -714,14 +759,18 @@ static int __init rapl_pmu_init(void)
 
 	pmu = __this_cpu_read(rapl_pmu);
 
-	pr_info("RAPL PMU detected, hw unit 2^-%d Joules,"
+	pr_info("RAPL PMU detected,"
 		" API unit is 2^-32 Joules,"
 		" %d fixed counters"
 		" %llu ms ovfl timer\n",
-		pmu->hw_unit,
 		hweight32(rapl_cntr_mask),
 		ktime_to_ms(pmu->timer_interval));
-
+	for (i = 0; i < NR_RAPL_DOMAINS; i++) {
+		if (rapl_cntr_mask & (1 << i)) {
+			pr_info("hw unit of domain %s 2^-%d Joules\n",
+				rapl_domain_names[i], rapl_hw_unit[i]);
+		}
+	}
 out:
 	cpu_notifier_register_done();
 
-- 
1.9.1

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