From: Stanislav Meduna <stano@meduna.org>
To: "linux-rt-users@vger.kernel.org" <linux-rt-users@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: timerfd read does not return [Was: Re: timerfd and softirqd]
Date: Thu, 18 Apr 2013 11:11:21 +0200 [thread overview]
Message-ID: <516FB8B9.9090506@meduna.org> (raw)
In-Reply-To: <516EC3F3.1080406@meduna.org>
Hi,
from a new log that includes syscall tracing it seems that a thread
waiting in a timerfd is woken, but does not return from the read:
TimerT d.... 3825.943136: sys_read -> 0x8
...
TimerT d.... 3825.943199: sys_read(fd: 6, buf: b7633158, count: 8)
TimerT d..3. 3825.943208: sched_switch: prev_comm=TimerT prev_prio=54 prev_state=S ==> next_comm=ksoftirqd/0 next_prio=62
ksoftirqd/0 ...1. 3825.943213: softirq_exit: vec=8 [action=HRTIMER]
...
OtherT d.h1. 3825.947983: irq_handler_entry: irq=0 name=timer
OtherT d.h3. 3825.947997: sched_wakeup: comm=SomeT1 prio=84 success=1
OtherT d.h3. 3825.948005: sched_wakeup: comm=SomeT2 prio=69 success=1
OtherT dNh1. 3825.948009: softirq_raise: vec=8 [action=HRTIMER]
OtherT dNh1. 3825.948011: softirq_raise: vec=1 [action=TIMER]
OtherT dNh1. 3825.948014: irq_handler_exit: irq=0 ret=handled
...
ksoftirqd/0 ...1. 3825.948034: softirq_entry: vec=1 [action=TIMER]
ksoftirqd/0 ...1. 3825.948037: softirq_exit: vec=1 [action=TIMER]
ksoftirqd/0 ...1. 3825.948039: softirq_entry: vec=8 [action=HRTIMER]
ksoftirqd/0 d..3. 3825.948047: sched_wakeup: comm=TimerT prio=54 success=1
ksoftirqd/0 d..3. 3825.948054: sched_switch: prev_comm=ksoftirqd/0 prev_prio=62 prev_state=R+ ==> next_comm=TimerT next_prio=54
TimerT d..4. 3825.948061: sched_pi_setprio: comm=ksoftirqd/0 oldprio=62 newprio=54
TimerT d..3. 3825.948072: sched_switch: prev_comm=TimerT prev_prio=54 prev_state=D ==> next_comm=ksoftirqd/0 next_prio=54
ksoftirqd/0 d..4. 3825.948079: sched_wakeup: comm=TimerT prio=54 success=1
ksoftirqd/0 d..3. 3825.948083: sched_pi_setprio: comm=ksoftirqd/0 oldprio=54 newprio=62
ksoftirqd/0 d..3. 3825.948093: sched_switch: prev_comm=ksoftirqd/0 prev_prio=62 prev_state=R+ ==> next_comm=TimerT next_prio=54
TimerT d.h1. 3825.948980: irq_handler_entry: irq=0 name=timer
TimerT d.h1. 3825.948991: softirq_raise: vec=1 [action=TIMER]
...
There is no return from the read until the RT throttler got activated.
Kernel version 3.4.25-rt37 - I'll check whether anything relevant
has changed since then.
Regards
--
Stano
next prev parent reply other threads:[~2013-04-18 9:11 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-15 11:02 hrtimer: interrupt took 6742 ns, then RT throttling and hung machine for nearly 2 seconds Stanislav Meduna
2013-04-15 11:54 ` Stanislav Meduna
2013-04-15 12:22 ` Thomas Gleixner
2013-04-15 12:56 ` Stanislav Meduna
2013-04-17 15:46 ` timerfd and softirqd [Was: Re: hrtimer: interrupt took 6742 ns, then RT throttling and hung machine for nearly 2 seconds] Stanislav Meduna
2013-04-18 9:11 ` Stanislav Meduna [this message]
2013-04-19 19:53 ` timerfd read does not return [Was: Re: timerfd and softirqd] Stanislav Meduna
2013-04-22 7:35 ` [PATCH] Re: timerfd read does not return Stanislav Meduna
2013-04-22 8:55 ` Stanislav Meduna
2013-04-27 8:34 ` timerfd read does not return - was probably fixed in 3.4.38 Stanislav Meduna
2013-04-28 11:53 ` Carsten Emde
2013-04-29 8:43 ` Stanislav Meduna
2013-05-02 20:02 ` Steven Rostedt
2013-05-10 12:42 ` timerfd read does not return - some traces Stanislav Meduna
2013-05-12 17:31 ` Stanislav Meduna
2013-05-12 23:20 ` timerfd read does not return - hangs inside put_user Stanislav Meduna
2013-05-13 8:05 ` timerfd read does not return - caused by MM fault Stanislav Meduna
2013-05-14 8:31 ` Livelock in handle_pte_fault [Was: Re: timerfd read does not return] Stanislav Meduna
2013-11-25 10:36 ` Vijay Katoch
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