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Commit 63f0c1d8 authored by Yan, Zheng's avatar Yan, Zheng Committed by Ingo Molnar
Browse files

perf/x86/intel: Track number of events that use the LBR callstack 



When enabling/disabling an event, check if the event uses the LBR
callstack feature, adjust the LBR callstack usage count accordingly.
Later patch will use the usage count to decide if LBR stack should
be saved/restored.

Signed-off-by: default avatarYan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: default avatarKan Liang <kan.liang@intel.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: eranian@google.com
Cc: jolsa@redhat.com
Link: http://lkml.kernel.org/r/1415156173-10035-9-git-send-email-kan.liang@intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent e18bf526

arch/x86/kernel/cpu/perf_event_intel_lbr.c

+19 −0
Original line number Diff line number Diff line
@@ -205,9 +205,15 @@ void intel_pmu_lbr_sched_task(struct perf_event_context *ctx, bool sched_in) 
	}

}



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 = this_cpu_ptr(&cpu_hw_events);

	struct x86_perf_task_context *task_ctx;



	if (!x86_pmu.lbr_nr)

		return;
@@ -222,6 +228,12 @@ void intel_pmu_lbr_enable(struct perf_event *event) 
	}

	cpuc->br_sel = event->hw.branch_reg.reg;



	if (branch_user_callstack(cpuc->br_sel) && event->ctx &&

					event->ctx->task_ctx_data) {

		task_ctx = event->ctx->task_ctx_data;

		task_ctx->lbr_callstack_users++;

	}



	cpuc->lbr_users++;

	perf_sched_cb_inc(event->ctx->pmu);

}
@@ -229,10 +241,17 @@ void intel_pmu_lbr_enable(struct perf_event *event) 
void intel_pmu_lbr_disable(struct perf_event *event)

{

	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);

	struct x86_perf_task_context *task_ctx;



	if (!x86_pmu.lbr_nr)

		return;



	if (branch_user_callstack(cpuc->br_sel) && event->ctx &&

					event->ctx->task_ctx_data) {

		task_ctx = event->ctx->task_ctx_data;

		task_ctx->lbr_callstack_users--;

	}



	cpuc->lbr_users--;

	WARN_ON_ONCE(cpuc->lbr_users < 0);

	perf_sched_cb_dec(event->ctx->pmu);