sched: Add a tracepoint to track rq->nr_running
Add a bare tracepoint trace_sched_update_nr_running_tp which tracks ->nr_running CPU's rq. This is used to accurately trace this data and provide a visualization of scheduler imbalances in, for example, the form of a heat map. The tracepoint is accessed by loading an external kernel module. An example module (forked from Qais' module and including the pelt related tracepoints) can be found at: https://github.com/auldp/tracepoints-helpers.git A script to turn the trace-cmd report output into a heatmap plot can be found at: https://github.com/jirvoz/plot-nr-running The tracepoints are added to add_nr_running() and sub_nr_running() which are in kernel/sched/sched.h. In order to avoid CREATE_TRACE_POINTS in the header a wrapper call is used and the trace/events/sched.h include is moved before sched.h in kernel/sched/core. Signed-off-by: Phil Auld <pauld@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200629192303.GC120228@lorien.usersys.redhat.com
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@ -2044,6 +2044,7 @@ const struct sched_avg *sched_trace_rq_avg_dl(struct rq *rq);
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const struct sched_avg *sched_trace_rq_avg_irq(struct rq *rq);
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int sched_trace_rq_cpu(struct rq *rq);
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int sched_trace_rq_nr_running(struct rq *rq);
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const struct cpumask *sched_trace_rd_span(struct root_domain *rd);
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@ -642,6 +642,10 @@ DECLARE_TRACE(sched_util_est_se_tp,
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TP_PROTO(struct sched_entity *se),
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TP_ARGS(se));
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DECLARE_TRACE(sched_update_nr_running_tp,
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TP_PROTO(struct rq *rq, int change),
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TP_ARGS(rq, change));
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#endif /* _TRACE_SCHED_H */
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/* This part must be outside protection */
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@ -6,6 +6,10 @@
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*
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* Copyright (C) 1991-2002 Linus Torvalds
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*/
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#define CREATE_TRACE_POINTS
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#include <trace/events/sched.h>
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#undef CREATE_TRACE_POINTS
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#include "sched.h"
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#include <linux/nospec.h>
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@ -23,9 +27,6 @@
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#include "pelt.h"
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#include "smp.h"
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#define CREATE_TRACE_POINTS
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#include <trace/events/sched.h>
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/*
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* Export tracepoints that act as a bare tracehook (ie: have no trace event
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* associated with them) to allow external modules to probe them.
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@ -38,6 +39,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_se_tp);
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EXPORT_TRACEPOINT_SYMBOL_GPL(sched_overutilized_tp);
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EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_cfs_tp);
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EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_se_tp);
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EXPORT_TRACEPOINT_SYMBOL_GPL(sched_update_nr_running_tp);
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DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
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@ -8195,4 +8197,7 @@ const u32 sched_prio_to_wmult[40] = {
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/* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
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};
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#undef CREATE_TRACE_POINTS
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void call_trace_sched_update_nr_running(struct rq *rq, int count)
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{
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trace_sched_update_nr_running_tp(rq, count);
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}
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@ -22,8 +22,6 @@
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*/
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#include "sched.h"
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#include <trace/events/sched.h>
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/*
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* Targeted preemption latency for CPU-bound tasks:
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*
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@ -11296,3 +11294,9 @@ const struct cpumask *sched_trace_rd_span(struct root_domain *rd)
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#endif
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}
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EXPORT_SYMBOL_GPL(sched_trace_rd_span);
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int sched_trace_rq_nr_running(struct rq *rq)
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{
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return rq ? rq->nr_running : -1;
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}
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EXPORT_SYMBOL_GPL(sched_trace_rq_nr_running);
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@ -28,8 +28,6 @@
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#include "sched.h"
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#include "pelt.h"
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#include <trace/events/sched.h>
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/*
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* Approximate:
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* val * y^n, where y^32 ~= 0.5 (~1 scheduling period)
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@ -76,6 +76,8 @@
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#include "cpupri.h"
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#include "cpudeadline.h"
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#include <trace/events/sched.h>
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#ifdef CONFIG_SCHED_DEBUG
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# define SCHED_WARN_ON(x) WARN_ONCE(x, #x)
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#else
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@ -97,6 +99,7 @@ extern atomic_long_t calc_load_tasks;
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extern void calc_global_load_tick(struct rq *this_rq);
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extern long calc_load_fold_active(struct rq *this_rq, long adjust);
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extern void call_trace_sched_update_nr_running(struct rq *rq, int count);
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/*
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* Helpers for converting nanosecond timing to jiffy resolution
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*/
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@ -1973,6 +1976,9 @@ static inline void add_nr_running(struct rq *rq, unsigned count)
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unsigned prev_nr = rq->nr_running;
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rq->nr_running = prev_nr + count;
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if (trace_sched_update_nr_running_tp_enabled()) {
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call_trace_sched_update_nr_running(rq, count);
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}
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#ifdef CONFIG_SMP
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if (prev_nr < 2 && rq->nr_running >= 2) {
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@ -1987,6 +1993,10 @@ static inline void add_nr_running(struct rq *rq, unsigned count)
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static inline void sub_nr_running(struct rq *rq, unsigned count)
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{
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rq->nr_running -= count;
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if (trace_sched_update_nr_running_tp_enabled()) {
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call_trace_sched_update_nr_running(rq, count);
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}
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/* Check if we still need preemption */
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sched_update_tick_dependency(rq);
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}
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