Messages in this thread Patch in this message | | | From | Phil Auld <> | Subject | [PATCH] Sched: Add a tracepoint to track rq->nr_running | Date | Fri, 19 Jun 2020 10:11:20 -0400 |
| |
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. Since sched.h includes trace/events/tlb.h via mmu_context.h we had to limit when CREATE_TRACE_POINTS is defined.
Signed-off-by: Phil Auld <pauld@redhat.com> CC: Qais Yousef <qais.yousef@arm.com> CC: Ingo Molnar <mingo@redhat.com> CC: Peter Zijlstra <peterz@infradead.org> CC: Vincent Guittot <vincent.guittot@linaro.org> CC: linux-kernel@vger.kernel.org --- include/trace/events/sched.h | 4 ++++ kernel/sched/core.c | 9 ++++----- kernel/sched/fair.c | 2 -- kernel/sched/pelt.c | 2 -- kernel/sched/sched.h | 12 ++++++++++++ 5 files changed, 20 insertions(+), 9 deletions(-)
diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h index ed168b0e2c53..a6d9fe5a68cf 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(int cpu, int change, unsigned int nr_running), + TP_ARGS(cpu, change, nr_running)); + #endif /* _TRACE_SCHED_H */ /* This part must be outside protection */ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 9a2fbf98fd6f..6f28fdff1d48 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6,7 +6,10 @@ * * Copyright (C) 1991-2002 Linus Torvalds */ + +#define SCHED_CREATE_TRACE_POINTS #include "sched.h" +#undef SCHED_CREATE_TRACE_POINTS #include <linux/nospec.h> @@ -21,9 +24,6 @@ #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 +34,7 @@ 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); @@ -7969,5 +7970,3 @@ const u32 sched_prio_to_wmult[40] = { /* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717, /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153, }; - -#undef CREATE_TRACE_POINTS diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index da3e5b54715b..fe5d9b6db8f7 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: * 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..6ae96679c169 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -75,6 +75,15 @@ #include "cpupri.h" #include "cpudeadline.h" +#ifdef SCHED_CREATE_TRACE_POINTS +#define CREATE_TRACE_POINTS +#endif +#include <trace/events/sched.h> + +#ifdef SCHED_CREATE_TRACE_POINTS +#undef CREATE_TRACE_POINTS +#endif + #ifdef CONFIG_SCHED_DEBUG # define SCHED_WARN_ON(x) WARN_ONCE(x, #x) #else @@ -1959,6 +1968,7 @@ static inline void add_nr_running(struct rq *rq, unsigned count) unsigned prev_nr = rq->nr_running; rq->nr_running = prev_nr + count; + trace_sched_update_nr_running_tp(cpu_of(rq), count, rq->nr_running); #ifdef CONFIG_SMP if (prev_nr < 2 && rq->nr_running >= 2) { @@ -1973,6 +1983,8 @@ 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; + trace_sched_update_nr_running_tp(cpu_of(rq), -count, rq->nr_running); + /* Check if we still need preemption */ sched_update_tick_dependency(rq); } -- 2.18.0
| |