From: Kan Liang <kan.li...@intel.com>
This patch special case per-cpu core_misc PMU events and allow them to
be part of any hardware/software group for system-wide monitoring.
An useful example would be to include the ASTATE/MSTATE event in a
sampling group. This can be used to calculate the frequency during each
sampling period, and track it over time.
A new context type (perf_free_context) is introduced to indicate these
per-cpu core misc PMU events. They are
- Free running counter
- Don't have any state to switch on context switch and never fails
to schedule
- No sampling support
- Only support system-wide monitoring
- per-cpu
We also defined a new PERF event type PERF_TYPE_CORE_MISC_FREE for them.
It's safe to mix cpu PMU events and CORE_MISC_FREE events in a group.
Because when cpu PMU events disable/enable, we can disable/enable
them at the same time without failure.
Since there is no sampling support for these events. They are only
available for group reading and system-wide monitoring.
Signed-off-by: Kan Liang <kan.li...@intel.com>
---
arch/x86/kernel/cpu/perf_event_intel_core_misc.c | 8 +++++---
include/linux/perf_event.h | 10 ++++++++++
include/linux/sched.h | 1 +
include/uapi/linux/perf_event.h | 1 +
kernel/events/core.c | 9 +++++++++
5 files changed, 26 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event_intel_core_misc.c
b/arch/x86/kernel/cpu/perf_event_intel_core_misc.c
index 4efe842..dad4495 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_core_misc.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_core_misc.c
@@ -889,7 +889,6 @@ static void __init core_misc_pmus_register(void)
type->pmu = (struct pmu) {
.attr_groups = type->pmu_group,
- .task_ctx_nr = perf_invalid_context,
.event_init = core_misc_pmu_event_init,
.add = core_misc_pmu_event_add, /* must have
*/
.del = core_misc_pmu_event_del, /* must have
*/
@@ -902,9 +901,12 @@ static void __init core_misc_pmus_register(void)
if (type->type == perf_intel_core_misc_thread) {
type->pmu.pmu_disable = (void *)
intel_core_misc_pmu_disable;
type->pmu.pmu_enable = (void *)
intel_core_misc_pmu_enable;
+ type->pmu.task_ctx_nr = perf_free_context;
+ err = perf_pmu_register(&type->pmu, type->name,
PERF_TYPE_CORE_MISC_FREE);
+ } else {
+ type->pmu.task_ctx_nr = perf_invalid_context;
+ err = perf_pmu_register(&type->pmu, type->name, -1);
}
-
- err = perf_pmu_register(&type->pmu, type->name, -1);
if (WARN_ON(err))
pr_info("Failed to register PMU %s error %d\n",
type->pmu.name, err);
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index fea0ddf..3538f1c 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -773,6 +773,16 @@ static inline int is_hardware_event(struct perf_event
*event)
return event->pmu->task_ctx_nr == perf_hw_context;
}
+static inline int is_free_event(struct perf_event *event)
+{
+ return event->pmu->task_ctx_nr == perf_free_context;
+}
+
+static inline int has_context_event(struct perf_event *event)
+{
+ return event->pmu->task_ctx_nr > perf_invalid_context;
+}
+
extern struct static_key perf_swevent_enabled[PERF_COUNT_SW_MAX];
extern void ___perf_sw_event(u32, u64, struct pt_regs *, u64);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index ae21f15..717f492 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1335,6 +1335,7 @@ union rcu_special {
struct rcu_node;
enum perf_event_task_context {
+ perf_free_context = -2,
perf_invalid_context = -1,
perf_hw_context = 0,
perf_sw_context,
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index d97f84c..232b674 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -32,6 +32,7 @@ enum perf_type_id {
PERF_TYPE_HW_CACHE = 3,
PERF_TYPE_RAW = 4,
PERF_TYPE_BREAKPOINT = 5,
+ PERF_TYPE_CORE_MISC_FREE = 6,
PERF_TYPE_MAX, /* non-ABI */
};
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 9077867..995b436 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8019,6 +8019,15 @@ SYSCALL_DEFINE5(perf_event_open,
}
/*
+ * Special case per-cpu free counter events and allow them to be part of
+ * any hardware/software group for system-wide monitoring.
+ */
+ if (group_leader && !task &&
+ is_free_event(event) &&
+ has_context_event(group_leader))
+ pmu = group_leader->pmu;
+
+ /*
* Get the target context (task or percpu):
*/
ctx = find_get_context(pmu, task, event);
--
1.8.3.1
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