From: Kan Liang <[email protected]> Multiplexing overhead is one of the key overhead when the number of events is more than available counters.
Signed-off-by: Kan Liang <[email protected]> --- include/linux/perf_event.h | 2 ++ include/uapi/linux/perf_event.h | 1 + kernel/events/core.c | 16 ++++++++++++++++ 3 files changed, 19 insertions(+) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 632647f..f72b97a 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -793,6 +793,8 @@ struct perf_cpu_context { struct list_head sched_cb_entry; int sched_cb_usage; + + struct perf_overhead_entry mux_overhead; }; struct perf_output_handle { diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index 071323d..9124c7c 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -993,6 +993,7 @@ struct perf_branch_entry { enum perf_record_overhead_type { PERF_NMI_OVERHEAD = 0, + PERF_MUX_OVERHEAD, PERF_OVERHEAD_MAX, }; diff --git a/kernel/events/core.c b/kernel/events/core.c index d82e6ca..9934059 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -1829,6 +1829,11 @@ event_sched_out(struct perf_event *event, if (event->attr.exclusive || !cpuctx->active_oncpu) cpuctx->exclusive = 0; + if (log_overhead && cpuctx->mux_overhead.nr) { + cpuctx->mux_overhead.cpu = smp_processor_id(); + perf_log_overhead(event, PERF_MUX_OVERHEAD, &cpuctx->mux_overhead); + } + perf_pmu_enable(event->pmu); } @@ -3330,9 +3335,17 @@ static void rotate_ctx(struct perf_event_context *ctx) list_rotate_left(&ctx->flexible_groups); } +static void +perf_caculate_mux_overhead(struct perf_cpu_context *cpuctx, u64 time) +{ + cpuctx->mux_overhead.nr++; + cpuctx->mux_overhead.time += time; +} + static int perf_rotate_context(struct perf_cpu_context *cpuctx) { struct perf_event_context *ctx = NULL; + u64 start_clock, end_clock; int rotate = 0; if (cpuctx->ctx.nr_events) { @@ -3349,6 +3362,7 @@ static int perf_rotate_context(struct perf_cpu_context *cpuctx) if (!rotate) goto done; + start_clock = perf_clock(); perf_ctx_lock(cpuctx, cpuctx->task_ctx); perf_pmu_disable(cpuctx->ctx.pmu); @@ -3364,6 +3378,8 @@ static int perf_rotate_context(struct perf_cpu_context *cpuctx) perf_pmu_enable(cpuctx->ctx.pmu); perf_ctx_unlock(cpuctx, cpuctx->task_ctx); + end_clock = perf_clock(); + perf_caculate_mux_overhead(cpuctx, end_clock - start_clock); done: return rotate; -- 2.5.5
