From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Steven Rostedt <rostedt@goodmis.org>,
Sebastian Siewior <bigeasy@linutronix.de>,
Anna-Maria Gleixner <anna-maria@linutronix.de>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Jiri Olsa <jolsa@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>,
Juergen Gross <jgross@suse.com>
Subject: [patch 09/12] hrtimer: Move unmarked hrtimers to soft interrupt expiry on RT
Date: Fri, 26 Jul 2019 20:30:57 +0200 [thread overview]
Message-ID: <20190726185753.551967692@linutronix.de> (raw)
In-Reply-To: 20190726183048.982726647@linutronix.de
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
On PREEMPT_RT not all hrtimers can be expired in hard interrupt context
even if that is perfectly fine on a PREEMPT_RT=n kernel, e.g. because they
take regular spinlocks. Also for latency reasons PREEMPT_RT tries to defer
most hrtimers' expiry into softirq context.
hrtimers marked with HRTIMER_MODE_HARD must be kept in hard interrupt
context expiry mode. Add the required logic.
No functional change for PREEMPT_RT=n kernels.
[ tglx: Split out of a larger combo patch. Added changelog ]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/time/hrtimer.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1271,8 +1271,16 @@ static void __hrtimer_init(struct hrtime
enum hrtimer_mode mode)
{
bool softtimer = !!(mode & HRTIMER_MODE_SOFT);
- int base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
struct hrtimer_cpu_base *cpu_base;
+ int base;
+
+ /*
+ * On PREEMPT_RT enabled kernels hrtimers which are not explicitely
+ * marked for hard interrupt expiry mode are moved into soft
+ * interrupt context for latency reasons.
+ */
+ if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(mode & HRTIMER_MODE_HARD))
+ softtimer = true;
memset(timer, 0, sizeof(struct hrtimer));
@@ -1286,6 +1294,7 @@ static void __hrtimer_init(struct hrtime
if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
clock_id = CLOCK_MONOTONIC;
+ base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
base += hrtimer_clockid_to_base(clock_id);
timer->is_soft = softtimer;
timer->base = &cpu_base->clock_base[base];
next prev parent reply other threads:[~2019-07-26 19:19 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-26 18:30 [patch 00/12] (hr)timers: Prepare for PREEMPT_RT support Thomas Gleixner
2019-07-26 18:30 ` [patch 01/12] hrtimer: Remove task argument from hrtimer_init_sleeper() Thomas Gleixner
2019-07-26 19:57 ` Steven Rostedt
2019-07-26 20:01 ` Thomas Gleixner
2019-07-30 22:07 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2019-07-26 18:30 ` [patch 02/12] hrtimer: Consolidate hrtimer_init() + hrtimer_init_sleeper() calls Thomas Gleixner
2019-07-30 22:08 ` [tip:timers/core] " tip-bot for Sebastian Andrzej Siewior
2019-08-01 15:49 ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` [patch 03/12] hrtimer: Introduce HARD expiry mode Thomas Gleixner
2019-07-30 22:10 ` [tip:timers/core] " tip-bot for Sebastian Andrzej Siewior
2019-08-01 15:52 ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` [patch 04/12] sched: Mark hrtimers to expire in hard interrupt context Thomas Gleixner
2019-07-30 22:11 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2019-08-01 15:53 ` tip-bot for Sebastian Andrzej Siewior
2019-08-01 18:58 ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` [patch 05/12] perf/core: " Thomas Gleixner
2019-07-30 22:12 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2019-08-01 15:54 ` tip-bot for Sebastian Andrzej Siewior
2019-08-01 18:59 ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` [patch 06/12] watchdog: Mark watchdog_hrtimer " Thomas Gleixner
2019-07-30 22:13 ` [tip:timers/core] " tip-bot for Sebastian Andrzej Siewior
2019-08-01 15:55 ` tip-bot for Sebastian Andrzej Siewior
2019-08-01 19:00 ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` [patch 07/12] KVM: LAPIC: Mark hrtimer " Thomas Gleixner
2019-07-26 19:41 ` Paolo Bonzini
2019-07-30 22:14 ` [tip:timers/core] " tip-bot for Sebastian Andrzej Siewior
2019-08-01 15:55 ` tip-bot for Sebastian Andrzej Siewior
2019-08-01 19:01 ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` [patch 08/12] tick: Mark tick related hrtimers to expiry " Thomas Gleixner
2019-07-30 22:14 ` [tip:timers/core] " tip-bot for Sebastian Andrzej Siewior
2019-08-01 15:56 ` tip-bot for Sebastian Andrzej Siewior
2019-08-01 19:01 ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` Thomas Gleixner [this message]
2019-07-30 22:15 ` [tip:timers/core] hrtimer: Move unmarked hrtimers to soft interrupt expiry on RT tip-bot for Sebastian Andrzej Siewior
2019-08-01 15:57 ` tip-bot for Sebastian Andrzej Siewior
2019-08-01 19:02 ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` [patch 10/12] hrtimer: Determine hard/soft expiry mode for hrtimer sleepers " Thomas Gleixner
2019-07-26 20:44 ` Steven Rostedt
2019-07-26 20:52 ` Thomas Gleixner
2019-07-26 20:56 ` Steven Rostedt
2019-07-26 21:16 ` Julia Cartwright
2019-07-26 21:30 ` Steven Rostedt
2019-07-26 21:35 ` Thomas Gleixner
2019-07-30 22:16 ` [tip:timers/core] " tip-bot for Sebastian Andrzej Siewior
2019-08-01 15:58 ` tip-bot for Sebastian Andrzej Siewior
2019-08-01 19:03 ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` [patch 11/12] hrtimer: Prepare support for PREEMPT_RT Thomas Gleixner
2019-07-28 9:06 ` Juergen Gross
2019-07-29 15:08 ` Steven Rostedt
2019-07-29 17:30 ` Paolo Bonzini
2019-07-31 8:45 ` Juergen Gross
2019-07-30 22:17 ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2019-08-01 15:58 ` tip-bot for Anna-Maria Gleixner
2019-08-01 19:04 ` tip-bot for Anna-Maria Gleixner
2019-08-20 13:26 ` Frederic Weisbecker
2019-08-23 2:12 ` [tip: timers/core] hrtimer: Improve comments on handling priority inversion against softirq kthread tip-bot2 for Frederic Weisbecker
2019-07-26 18:31 ` [patch 12/12] timers: Prepare support for PREEMPT_RT Thomas Gleixner
2019-07-30 22:17 ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2019-08-01 15:59 ` tip-bot for Anna-Maria Gleixner
2019-08-01 19:04 ` tip-bot for Anna-Maria Gleixner
2019-07-29 19:45 ` [patch 00/12] (hr)timers: Prepare for PREEMPT_RT support Peter Zijlstra
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