From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org,
linux-rt-users <linux-rt-users@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Carsten Emde <C.Emde@osadl.org>, John Kacur <jkacur@redhat.com>
Subject: [PATCH RT 02/12] Latency histograms: Adjust timer, if already elapsed when programmed
Date: Tue, 17 Jul 2012 11:31:17 -0400 [thread overview]
Message-ID: <20120717153242.943096035@goodmis.org> (raw)
In-Reply-To: 20120717153115.606116459@goodmis.org
[-- Attachment #1: 0002-Latency-histograms-Adjust-timer-if-already-elapsed-w.patch --]
[-- Type: text/plain, Size: 2129 bytes --]
From: Carsten Emde <C.Emde@osadl.org>
Nothing prevents a programmer from calling clock_nanosleep() with an
already elapsed wakeup time in absolute time mode or with a too small
delay in relative time mode. Such timers cannot wake up in time and,
thus, should be corrected when entered into the missed timers latency
histogram (CONFIG_MISSED_TIMERS_HIST).
This patch marks such timers and uses a corrected expiration time.
Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/hrtimer.h | 3 +++
kernel/hrtimer.c | 16 ++++++++++++++--
2 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 0e37086..7408760 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -113,6 +113,9 @@ struct hrtimer {
unsigned long state;
struct list_head cb_entry;
int irqsafe;
+#ifdef CONFIG_MISSED_TIMER_OFFSETS_HIST
+ ktime_t praecox;
+#endif
#ifdef CONFIG_TIMER_STATS
int start_pid;
void *start_site;
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 3991464..a080e62 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -1021,6 +1021,17 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
#endif
}
+#ifdef CONFIG_MISSED_TIMER_OFFSETS_HIST
+ {
+ ktime_t now = new_base->get_time();
+
+ if (ktime_to_ns(tim) < ktime_to_ns(now))
+ timer->praecox = now;
+ else
+ timer->praecox = ktime_set(0, 0);
+ }
+#endif
+
hrtimer_set_expires_range_ns(timer, tim, delta_ns);
timer_stats_hrtimer_set_start_info(timer);
@@ -1458,8 +1469,9 @@ retry:
timer = container_of(node, struct hrtimer, node);
trace_hrtimer_interrupt(raw_smp_processor_id(),
- ktime_to_ns(ktime_sub(
- hrtimer_get_expires(timer), basenow)),
+ ktime_to_ns(ktime_sub(ktime_to_ns(timer->praecox) ?
+ timer->praecox : hrtimer_get_expires(timer),
+ basenow)),
current,
timer->function == hrtimer_wakeup ?
container_of(timer, struct hrtimer_sleeper,
--
1.7.10.4
next prev parent reply other threads:[~2012-07-17 15:31 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-17 15:31 [PATCH RT 00/12] [ANNOUNCE] 3.4.4-rt14-rc2 stable review Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 01/12] Latency histogramms: Cope with backwards running local trace clock Steven Rostedt
2012-07-17 15:31 ` Steven Rostedt [this message]
2012-07-17 15:31 ` [PATCH RT 03/12] Disable RT_GROUP_SCHED in PREEMPT_RT_FULL Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 04/12] Latency histograms: Detect another yet overlooked sharedprio condition Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 05/12] slab: Prevent local lock deadlock Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 06/12] fs, jbd: pull your plug when waiting for space Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 07/12] perf: Make swevent hrtimer run in irq instead of softirq Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 08/12] cpu/rt: Rework cpu down for PREEMPT_RT Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 09/12] cpu/rt: Fix cpu_hotplug variable initialization Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 10/12] workqueue: Revert workqueue: Fix PF_THREAD_BOUND abuse Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 11/12] workqueue: Revert workqueue: Fix cpuhotplug trainwreck Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 12/12] Linux 3.4.4-rt14-rc2 Steven Rostedt
-- strict thread matches above, loose matches on Subject: below --
2012-07-18 22:39 [PATCH RT 00/12] [ANNOUNCE] 3.0.36-rt58-rc1 stable review Steven Rostedt
2012-07-18 22:39 ` [PATCH RT 02/12] Latency histograms: Adjust timer, if already elapsed when programmed Steven Rostedt
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