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Subject[PATCH 09/15] perf: Track system-wide LBR users and LBR callstack users
Date
From: "Yan, Zheng" <zheng.z.yan@intel.com>

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
---
arch/x86/kernel/cpu/perf_event.h | 1 +
arch/x86/kernel/cpu/perf_event_intel_lbr.c | 25 ++++++++++++++++++++++++-
2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h
index 3ed9629..bcc8e1f 100644
--- a/arch/x86/kernel/cpu/perf_event.h
+++ b/arch/x86/kernel/cpu/perf_event.h
@@ -150,6 +150,7 @@ struct cpu_hw_events {
* Intel LBR bits
*/
int lbr_users;
+ int lbr_sys_users;
struct perf_branch_stack lbr_stack;
struct perf_branch_entry lbr_entries[MAX_LBR_ENTRIES];
struct er_account *lbr_sel;
diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
index c33bf84c..f57960d 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
@@ -201,15 +201,29 @@ void intel_pmu_lbr_sched_task(struct perf_event_context *ctx, bool sched_in)
intel_pmu_lbr_reset();
}

+static inline bool branch_user_callstack(unsigned br_sel)
+{
+ return (br_sel & X86_BR_USER) && (br_sel & X86_BR_CALL_STACK);
+}
+
void intel_pmu_lbr_enable(struct perf_event *event)
{
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+ struct x86_perf_task_context *task_ctx;

if (!x86_pmu.lbr_nr)
return;

+ cpuc = &__get_cpu_var(cpu_hw_events);
+ task_ctx = event->ctx ? event->ctx->task_ctx_data : NULL;
+
cpuc->br_sel = event->hw.branch_reg.reg;

+ if (!(event->attach_state & PERF_ATTACH_TASK))
+ cpuc->lbr_sys_users++;
+ else if (branch_user_callstack(cpuc->br_sel))
+ task_ctx->lbr_callstack_users++;
+
cpuc->lbr_users++;
if (cpuc->lbr_users == 1)
perf_sched_cb_enable(event->ctx->pmu);
@@ -217,11 +231,20 @@ void intel_pmu_lbr_enable(struct perf_event *event)

void intel_pmu_lbr_disable(struct perf_event *event)
{
- struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+ struct cpu_hw_events *cpuc;
+ struct x86_perf_task_context *task_ctx;

if (!x86_pmu.lbr_nr)
return;

+ cpuc = &__get_cpu_var(cpu_hw_events);
+ task_ctx = event->ctx ? event->ctx->task_ctx_data : NULL;
+
+ if (!(event->attach_state & PERF_ATTACH_TASK))
+ cpuc->lbr_sys_users--;
+ else if (branch_user_callstack(cpuc->br_sel))
+ task_ctx->lbr_callstack_users--;
+
cpuc->lbr_users--;
WARN_ON_ONCE(cpuc->lbr_users < 0);

--
1.8.1.4


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