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

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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: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Peter 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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Yan, Zheng 2014-11-04 21:56:04 -05:00 committed by Ingo Molnar
parent e18bf52642
commit 63f0c1d841
1 changed files with 19 additions and 0 deletions
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19
arch/x86/kernel/cpu/perf_event_intel_lbr.c
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@ -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);