From: Alistair John Strachan <s0348365@sms.ed.ac.uk>
To: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>
Subject: Realtime Preemption, 2.6.12, Beginners Guide?
Date: Wed, 6 Jul 2005 12:57:36 +0100 [thread overview]
Message-ID: <200507061257.36738.s0348365@sms.ed.ac.uk> (raw)
Hi,
Today I decided to try Ingo's rt-preempt patch on 2.6.12 (V0.7.51-02). I'm
most interested in the CONFIG_PREEMPT_RT mode, so I selected this option
instead of the others. I enabled a couple of the debugging options, but I
wasn't totally clear on which options are most useful, so I just enabled the
ones that didn't have a warning about significant overhead, namely..
CONFIG_DETECT_SOFTLOCKUP=y
CONFIG_WAKEUP_TIMING=y
CONFIG_CRITICAL_TIMING=y
CONFIG_LATENCY_TIMING=y
Additionally (by mistake) I enabled:
CONFIG_CRITICAL_IRQSOFF_TIMING=y
Which does mention overhead.
Which debugging options are most useful for testing purposes? Is what I've
selected enough? Also, I got a few unexpected messages in dmesg on bootup.
Firstly;
spawn_desched_task(00000000)
desched cpu_callback 3/00000000
ksoftirqd started up.
softirq RT prio: 24.
ksoftirqd started up.
softirq RT prio: 24.
[...]
desched cpu_callback 2/00000000
desched thread 0 started up.
softlockup thread 0 started up.
Why does it print out the same ksoftirqd message six times? Is this expected
behaviour? Next, I got a warning about CONFIG_CRITICAL_IRQSOFF_TIMING;
should this option be enabled?
Finally, I got this:
BUG: soft lockup detected on CPU#0!
[<c013d7e9>] softlockup_tick+0x89/0xb0 (8)
[<c0108590>] timer_interrupt+0x50/0xf0 (20)
[<c013da91>] handle_IRQ_event+0x81/0x100 (16)
[<c013dbfc>] __do_IRQ+0xec/0x190 (48)
[<c0105a28>] do_IRQ+0x48/0x70 (40)
=======================
[<c024df3b>] acpi_processor_idle+0x0/0x258 (8)
[<c0103d03>] common_interrupt+0x1f/0x24 (12)
[<c024df3b>] acpi_processor_idle+0x0/0x258 (4)
[<c024e05e>] acpi_processor_idle+0x123/0x258 (40)
[<c024df3b>] acpi_processor_idle+0x0/0x258 (32)
[<c0101116>] cpu_idle+0x56/0x80 (16)
[<c03a486c>] start_kernel+0x17c/0x1c0 (12)
[<c03a43b0>] unknown_bootoption+0x0/0x1f0 (20)
I think it's when my scripts try to set up the IrDA port; the script runs the
following (I have a weird broken NC6000 IrDA port which needs messing around
with to work)..
/usr/bin/smcinit -v -s 0x3E8 -f 0x130 -i 4 -d 3 >/dev/null
Of course, the message could've just been coincidental, as it doesn't actually
refer to the smcs driver at all.
I set preempt_max_latency to zero, but the only messages I've got back from
the kernel so far are:
( softirq-timer/0-3 |#0): new 3 us maximum-latency wakeup.
( softirq-timer/0-3 |#0): new 1003 us maximum-latency wakeup.
( softirq-timer/0-3 |#0): new 1001 us maximum-latency wakeup.
Which is presumably a good sign.
--
Cheers,
Alistair.
personal: alistair()devzero!co!uk
university: s0348365()sms!ed!ac!uk
student: CS/CSim Undergraduate
contact: 1F2 55 South Clerk Street,
Edinburgh. EH8 9PP.
next reply other threads:[~2005-07-06 16:18 UTC|newest]
Thread overview: 101+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-07-06 11:57 Alistair John Strachan [this message]
2005-07-06 12:51 ` Realtime Preemption, 2.6.12, Beginners Guide? Alistair John Strachan
2005-07-06 13:39 ` Ingo Molnar
2005-07-06 15:58 ` Alistair John Strachan
2005-07-06 16:28 ` Ingo Molnar
2005-07-06 16:31 ` Alistair John Strachan
2005-07-06 13:31 ` Ingo Molnar
2005-07-06 15:55 ` Alistair John Strachan
2005-07-06 16:24 ` Ingo Molnar
2005-07-06 16:37 ` Alistair John Strachan
2005-07-06 16:56 ` Alistair John Strachan
2005-07-06 17:01 ` Ingo Molnar
2005-07-06 17:14 ` Alistair John Strachan
2005-07-06 17:27 ` Ingo Molnar
2005-07-06 18:23 ` Alistair John Strachan
2005-07-06 18:38 ` Ingo Molnar
2005-07-06 18:41 ` Ingo Molnar
2005-07-06 19:47 ` Alistair John Strachan
2005-07-06 20:44 ` Ingo Molnar
2005-07-06 21:00 ` Alistair John Strachan
2005-07-06 21:02 ` Ingo Molnar
2005-07-06 22:15 ` Alistair John Strachan
2005-07-06 23:08 ` Fernando Lopez-Lezcano
2005-07-07 6:04 ` Michal Schmidt
2005-07-07 10:25 ` Ingo Molnar
2005-07-07 9:46 ` Alistair John Strachan
2005-07-07 11:21 ` Alistair John Strachan
2005-07-07 11:29 ` Ingo Molnar
2005-07-07 11:37 ` Alistair John Strachan
2005-07-07 11:42 ` Ingo Molnar
2005-07-07 12:15 ` Alistair John Strachan
2005-07-07 12:29 ` Ingo Molnar
2005-07-07 13:38 ` Alistair John Strachan
2005-07-07 12:33 ` Alistair John Strachan
2005-07-08 9:47 ` Alistair John Strachan
2005-07-08 11:46 ` Ingo Molnar
2005-07-08 18:38 ` Alistair John Strachan
2005-07-08 19:12 ` USB storage does not work with 3GB of RAM, but does with 2G of RAM Jon Schindler
2005-07-08 19:25 ` Realtime Preemption, 2.6.12, Beginners Guide? Ingo Molnar
2005-07-08 19:31 ` Ingo Molnar
2005-07-08 19:34 ` Ingo Molnar
2005-07-08 19:48 ` Ingo Molnar
2005-07-08 19:55 ` Alistair John Strachan
2005-07-08 20:45 ` Alistair John Strachan
2005-07-09 11:58 ` Ingo Molnar
2005-07-09 14:07 ` Alistair John Strachan
2005-07-09 14:55 ` Ingo Molnar
2005-07-09 15:57 ` Ingo Molnar
2005-07-09 16:02 ` Ingo Molnar
2005-07-09 16:04 ` Alistair John Strachan
2005-07-11 13:55 ` Alistair John Strachan
2005-07-11 14:12 ` Ingo Molnar
2005-07-11 14:16 ` Ingo Molnar
2005-07-11 14:38 ` Alistair John Strachan
2005-07-11 14:43 ` Ingo Molnar
2005-07-11 15:50 ` Alistair John Strachan
2005-07-13 14:45 ` Ingo Molnar
2005-07-13 15:30 ` Ingo Molnar
2005-07-14 19:58 ` Alistair John Strachan
2005-07-14 20:16 ` Lee Revell
2005-07-15 22:12 ` Alistair John Strachan
2005-07-12 2:56 ` Lee Revell
2005-07-11 15:07 ` Ingo Molnar
2005-07-12 20:09 ` Lee Revell
2005-07-12 21:01 ` Chuck Harding
2005-07-13 10:39 ` Ingo Molnar
2005-07-13 12:29 ` Gene Heskett
2005-07-13 14:01 ` K.R. Foley
2005-07-13 19:41 ` Chuck Harding
2005-07-13 19:45 ` Ingo Molnar
2005-07-14 13:39 ` K.R. Foley
2005-07-14 12:50 ` Karsten Wiese
2005-07-14 13:56 ` K.R. Foley
2005-07-14 14:10 ` K.R. Foley
2005-07-14 14:11 ` K.R. Foley
2005-07-14 19:49 ` Chuck Harding
2005-07-16 17:15 ` Ingo Molnar
2005-07-16 19:01 ` K.R. Foley
2005-07-17 12:07 ` Karsten Wiese
2005-07-18 15:46 ` K.R. Foley
2005-07-19 11:14 ` Karsten Wiese
2005-07-19 13:35 ` Gene Heskett
2005-07-19 13:57 ` Ingo Molnar
2005-07-19 15:19 ` Gene Heskett
2005-07-19 23:00 ` Karsten Wiese
2005-07-09 12:41 ` Ingo Molnar
2005-07-09 12:46 ` Ingo Molnar
2005-07-09 13:05 ` Ingo Molnar
2005-07-11 22:48 ` William Weston
2005-07-12 13:53 ` Ingo Molnar
2005-07-09 13:13 ` Ingo Molnar
2005-07-09 13:26 ` Ingo Molnar
2005-07-10 19:01 ` PCMCIA stack reduction patch [Was: Re: Realtime Preemption, 2.6.12, Beginners Guide?] Dominik Brodowski
2005-07-09 13:36 ` Realtime Preemption, 2.6.12, Beginners Guide? Ingo Molnar
2005-07-11 13:28 ` Paulo Marques
2005-07-08 11:48 ` Ingo Molnar
2005-07-08 17:42 ` Alistair John Strachan
2005-07-08 17:48 ` Jakub Jelinek
2005-07-08 18:12 ` Alistair John Strachan
[not found] <20050713063310.GA12661@elte.hu>
2005-07-13 10:30 ` karsten wiese
2005-07-13 18:38 ` Chuck Harding
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