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 <pa...@redhat.com> CC: Qais Yousef <qais.you...@arm.com> CC: Ingo Molnar <mi...@redhat.com> CC: Peter Zijlstra <pet...@infradead.org> CC: Vincent Guittot <vincent.guit...@linaro.org> CC: Steven Rostedt <rost...@goodmis.org> CC: linux-kernel@vger.kernel.org --- V2: Fix use of tracepoint in header from Steven. Pass rq* and use helper to get nr_running field, from Qais. include/linux/sched.h | 1 + include/trace/events/sched.h | 4 ++++ kernel/sched/core.c | 13 +++++++++---- kernel/sched/fair.c | 8 ++++++-- kernel/sched/pelt.c | 2 -- kernel/sched/sched.h | 10 ++++++++++ 6 files changed, 30 insertions(+), 8 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 4418f5cb8324..5f114faf2247 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2015,6 +2015,7 @@ const struct sched_avg *sched_trace_rq_avg_dl(struct rq *rq); const struct sched_avg *sched_trace_rq_avg_irq(struct rq *rq); int sched_trace_rq_cpu(struct rq *rq); +int sched_trace_rq_nr_running(struct rq *rq); const struct cpumask *sched_trace_rd_span(struct root_domain *rd); diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h index ed168b0e2c53..8c72f9113694 100644 --- a/include/trace/events/sched.h +++ b/include/trace/events/sched.h @@ -634,6 +634,10 @@ DECLARE_TRACE(sched_overutilized_tp, TP_PROTO(struct root_domain *rd, bool overutilized), TP_ARGS(rd, overutilized)); +DECLARE_TRACE(sched_update_nr_running_tp, + TP_PROTO(struct rq *rq, int change), + TP_ARGS(rq, change)); + #endif /* _TRACE_SCHED_H */ /* This part must be outside protection */ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 9a2fbf98fd6f..0d35d7c4c330 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6,6 +6,10 @@ * * Copyright (C) 1991-2002 Linus Torvalds */ +#define CREATE_TRACE_POINTS +#include <trace/events/sched.h> +#undef CREATE_TRACE_POINTS + #include "sched.h" #include <linux/nospec.h> @@ -21,9 +25,6 @@ #include "pelt.h" -#define CREATE_TRACE_POINTS -#include <trace/events/sched.h> - /* * Export tracepoints that act as a bare tracehook (ie: have no trace event * associated with them) to allow external modules to probe them. @@ -34,6 +35,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_dl_tp); EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_irq_tp); EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_se_tp); EXPORT_TRACEPOINT_SYMBOL_GPL(sched_overutilized_tp); +EXPORT_TRACEPOINT_SYMBOL_GPL(sched_update_nr_running_tp); DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); @@ -7970,4 +7972,7 @@ const u32 sched_prio_to_wmult[40] = { /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153, }; -#undef CREATE_TRACE_POINTS +void call_trace_sched_update_nr_running(struct rq *rq, int count) +{ + trace_sched_update_nr_running_tp(rq, count); +} diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index da3e5b54715b..2e2f3f68e318 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -22,8 +22,6 @@ */ #include "sched.h" -#include <trace/events/sched.h> - /* * Targeted preemption latency for CPU-bound tasks: * @@ -11293,3 +11291,9 @@ const struct cpumask *sched_trace_rd_span(struct root_domain *rd) #endif } EXPORT_SYMBOL_GPL(sched_trace_rd_span); + +int sched_trace_rq_nr_running(struct rq *rq) +{ + return rq ? rq->nr_running : -1; +} +EXPORT_SYMBOL_GPL(sched_trace_rq_nr_running); diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c index b647d04d9c8b..bb69a0ae8d6c 100644 --- a/kernel/sched/pelt.c +++ b/kernel/sched/pelt.c @@ -28,8 +28,6 @@ #include "sched.h" #include "pelt.h" -#include <trace/events/sched.h> - /* * Approximate: * val * y^n, where y^32 ~= 0.5 (~1 scheduling period) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index db3a57675ccf..e621eaa44474 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -75,6 +75,8 @@ #include "cpupri.h" #include "cpudeadline.h" +#include <trace/events/sched.h> + #ifdef CONFIG_SCHED_DEBUG # define SCHED_WARN_ON(x) WARN_ONCE(x, #x) #else @@ -96,6 +98,7 @@ extern atomic_long_t calc_load_tasks; extern void calc_global_load_tick(struct rq *this_rq); extern long calc_load_fold_active(struct rq *this_rq, long adjust); +extern void call_trace_sched_update_nr_running(struct rq *rq, int count); /* * Helpers for converting nanosecond timing to jiffy resolution */ @@ -1959,6 +1962,9 @@ static inline void add_nr_running(struct rq *rq, unsigned count) unsigned prev_nr = rq->nr_running; rq->nr_running = prev_nr + count; + if (trace_sched_update_nr_running_tp_enabled()) { + call_trace_sched_update_nr_running(rq, count); + } #ifdef CONFIG_SMP if (prev_nr < 2 && rq->nr_running >= 2) { @@ -1973,6 +1979,10 @@ static inline void add_nr_running(struct rq *rq, unsigned count) static inline void sub_nr_running(struct rq *rq, unsigned count) { rq->nr_running -= count; + if (trace_sched_update_nr_running_tp_enabled()) { + call_trace_sched_update_nr_running(rq, count); + } + /* Check if we still need preemption */ sched_update_tick_dependency(rq); } -- 2.18.0 --
