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perf/x86/intel: Track the num of events needs late setup

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When a machine supports PEBS v6, perf unconditionally searches the
cpuc->event_list[] for every event and check if the late setup is
required, which is unnecessary.

The late setup is only required for special events, e.g., events support
counters snapshotting feature. Add n_late_setup to track the num of
events that needs the late setup.

Other features, e.g., auto counter reload feature, require the late
setup as well. Add a wrapper, intel_pmu_pebs_late_setup, for the events
that support counters snapshotting feature.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Thomas Falcon <thomas.falcon@intel.com>
Link: https://lkml.kernel.org/r/20250327195217.2683619-3-kan.liang@linux.intel.com
This commit is contained in:
Kan Liang 2025-03-27 12:52:14 -07:00 committed by Peter Zijlstra
parent 4dfe3232cc
commit 0a6557938d
3 changed files with 20 additions and 2 deletions
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14
arch/x86/events/intel/core.c
View File

@ -2603,6 +2603,8 @@ static void intel_pmu_del_event(struct perf_event *event)
intel_pmu_lbr_del(event);
if (event->attr.precise_ip)
intel_pmu_pebs_del(event);
if (is_pebs_counter_event_group(event))
this_cpu_ptr(&cpu_hw_events)->n_late_setup--;
}
static int icl_set_topdown_event_period(struct perf_event *event)
@ -2914,12 +2916,24 @@ static void intel_pmu_enable_event(struct perf_event *event)
}
}
void intel_pmu_late_setup(void)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
if (!cpuc->n_late_setup)
return;
intel_pmu_pebs_late_setup(cpuc);
}
static void intel_pmu_add_event(struct perf_event *event)
{
if (event->attr.precise_ip)
intel_pmu_pebs_add(event);
if (intel_pmu_needs_branch_stack(event))
intel_pmu_lbr_add(event);
if (is_pebs_counter_event_group(event))
this_cpu_ptr(&cpu_hw_events)->n_late_setup++;
}
/*

3
arch/x86/events/intel/ds.c
View File

@ -1355,9 +1355,8 @@ static void __intel_pmu_pebs_update_cfg(struct perf_event *event,
}
static void intel_pmu_late_setup(void)
void intel_pmu_pebs_late_setup(struct cpu_hw_events *cpuc)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
struct perf_event *event;
u64 pebs_data_cfg = 0;
int i;

5
arch/x86/events/perf_event.h
View File

@ -261,6 +261,7 @@ struct cpu_hw_events {
struct event_constraint *event_constraint[X86_PMC_IDX_MAX];
int n_excl; /* the number of exclusive events */
int n_late_setup; /* the num of events needs late setup */
unsigned int txn_flags;
int is_fake;
@ -1581,6 +1582,8 @@ void intel_pmu_disable_bts(void);
int intel_pmu_drain_bts_buffer(void);
void intel_pmu_late_setup(void);
u64 grt_latency_data(struct perf_event *event, u64 status);
u64 cmt_latency_data(struct perf_event *event, u64 status);
@ -1637,6 +1640,8 @@ void intel_pmu_pebs_disable_all(void);
void intel_pmu_pebs_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in);
void intel_pmu_pebs_late_setup(struct cpu_hw_events *cpuc);
void intel_pmu_drain_pebs_buffer(void);
void intel_pmu_store_pebs_lbrs(struct lbr_entry *lbr);