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From: Jiri Olsa <jolsa@kernel.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: lkml <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	David Ahern <dsahern@gmail.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Stephane Eranian <eranian@google.com>,
	Milian Wolff <milian.wolff@kdab.com>,
	Andi Kleen <andi@firstfloor.org>,
	Frederic Weisbecker <frederic@kernel.org>
Subject: [PATCH 09/10] perf/cputime: Don't stop idle tick if there's live cputime event
Date: Thu,  7 Jun 2018 00:15:12 +0200	[thread overview]
Message-ID: <20180606221513.11302-10-jolsa@kernel.org> (raw)
In-Reply-To: <20180606221513.11302-1-jolsa@kernel.org>

Disable stopping of the idle tick when having live cputime
event. When the tick is disabled, the idle counts are out
of date until next tick/update and perf cputime PMU provides
misleading counts.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 include/linux/perf_event.h |  1 +
 kernel/events/cputime.c    | 13 +++++++++++++
 kernel/time/tick-sched.c   |  4 ++++
 3 files changed, 18 insertions(+)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index aa9eaab370be..ba61d2f9602a 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1407,4 +1407,5 @@ int perf_event_exit_cpu(unsigned int cpu);
 #define perf_event_exit_cpu	NULL
 #endif
 
+bool has_cputime_event(int cpu);
 #endif /* _LINUX_PERF_EVENT_H */
diff --git a/kernel/events/cputime.c b/kernel/events/cputime.c
index efad24543f13..32d3cde0047e 100644
--- a/kernel/events/cputime.c
+++ b/kernel/events/cputime.c
@@ -1,6 +1,7 @@
 #include <linux/kernel_stat.h>
 #include <linux/sched.h>
 #include <linux/perf_event.h>
+#include <linux/tick.h>
 
 enum perf_cputime_id {
 	PERF_CPUTIME_USER,
@@ -16,6 +17,13 @@ enum perf_cputime_id {
 	PERF_CPUTIME_MAX,
 };
 
+static DEFINE_PER_CPU(int, has_cputime);
+
+bool has_cputime_event(int cpu)
+{
+	return per_cpu(has_cputime, cpu) != 0;
+}
+
 static enum cpu_usage_stat map[PERF_CPUTIME_MAX] = {
 	[PERF_CPUTIME_USER]		= CPUTIME_USER,
 	[PERF_CPUTIME_NICE]		= CPUTIME_NICE,
@@ -143,12 +151,17 @@ static int cputime_event_add(struct perf_event *event, int flags)
 	if (flags & PERF_EF_START)
 		cputime_event_start(event, flags);
 
+	if (event->hw.config == PERF_CPUTIME_IDLE)
+		tick_nohz_idle_restart_tick();
+
+	this_cpu_inc(has_cputime);
 	return 0;
 }
 
 static void cputime_event_del(struct perf_event *event, int flags)
 {
 	cputime_event_stop(event, PERF_EF_UPDATE);
+	this_cpu_dec(has_cputime);
 }
 
 static void perf_cputime_read(struct perf_event *event)
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index da9455a6b42b..1c105bc2a92e 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -28,6 +28,7 @@
 #include <linux/posix-timers.h>
 #include <linux/context_tracking.h>
 #include <linux/mm.h>
+#include <linux/perf_event.h>
 
 #include <asm/irq_regs.h>
 
@@ -912,6 +913,9 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
 			return false;
 	}
 
+	if (has_cputime_event(cpu))
+		return false;
+
 	return true;
 }
 
-- 
2.13.6

  parent reply	other threads:[~2018-06-06 22:16 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-06 22:15 [RFC 00/10] perf: Add cputime events/metrics Jiri Olsa
2018-06-06 22:15 ` [PATCH 01/10] perf tools: Uniquify the event name if there's no other matched event Jiri Olsa
2018-06-06 23:19   ` Andi Kleen
2018-06-07  6:22     ` Jiri Olsa
2018-06-07 16:09       ` Stephane Eranian
2018-06-08  0:06         ` Jiri Olsa
2018-06-06 22:15 ` [PATCH 02/10] perf tools: Fix error index for pmu event parser Jiri Olsa
2018-06-07 18:53   ` Arnaldo Carvalho de Melo
2018-06-14  6:21   ` [tip:perf/urgent] " tip-bot for Jiri Olsa
2018-06-06 22:15 ` [PATCH 03/10] perf stat: Add --interval-clear option Jiri Olsa
2018-06-07 18:57   ` Arnaldo Carvalho de Melo
2018-06-14  6:21   ` [tip:perf/urgent] " tip-bot for Jiri Olsa
2018-06-06 22:15 ` [PATCH 04/10] perf stat: Use only color_fprintf call in print_metric_only Jiri Olsa
2018-06-07 19:00   ` Arnaldo Carvalho de Melo
2018-06-14  6:22   ` [tip:perf/urgent] " tip-bot for Jiri Olsa
2018-06-06 22:15 ` [PATCH 05/10] perf stat: Fix metric column display Jiri Olsa
2018-06-07 19:00   ` Arnaldo Carvalho de Melo
2018-06-14  6:22   ` [tip:perf/urgent] perf stat: Fix metric column header display alignment tip-bot for Jiri Olsa
2018-06-06 22:15 ` [PATCH 06/10] perf stat: Allow to specify specific metric column len Jiri Olsa
2018-06-14  6:23   ` [tip:perf/urgent] " tip-bot for Jiri Olsa
2018-06-06 22:15 ` [PATCH 07/10] perf stat: Add event parsing error handling to add_default_attributes Jiri Olsa
2018-06-07 19:04   ` Arnaldo Carvalho de Melo
2018-06-07 19:05     ` Arnaldo Carvalho de Melo
2018-06-14  6:23   ` [tip:perf/urgent] " tip-bot for Jiri Olsa
2018-06-06 22:15 ` [PATCH 08/10] perf/cputime: Add cputime pmu Jiri Olsa
2018-06-06 22:15 ` Jiri Olsa [this message]
2018-06-07 15:45   ` [PATCH 09/10] perf/cputime: Don't stop idle tick if there's live cputime event Andi Kleen
2018-06-07 16:01     ` Stephane Eranian
2018-06-08  0:12       ` Jiri Olsa
2018-06-06 22:15 ` [PATCH 10/10] perf stat: Add cputime metric support Jiri Olsa
2018-06-06 23:10 ` [RFC 00/10] perf: Add cputime events/metrics Andi Kleen
2018-09-26 14:44   ` Milian Wolff
2018-09-26 21:48     ` Jiri Olsa

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