From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: TAO HU <tghk48@motorola.com>
Cc: Don Zickus <dzickus@redhat.com>, Ingo Molnar <mingo@elte.hu>,
linux-omap <linux-omap@vger.kernel.org>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: In many cases softlockup can not be reported after disabling IRQ for long time
Date: Thu, 2 Feb 2012 08:43:50 +0000 [thread overview]
Message-ID: <20120202084350.GB1275@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <CAOwKts8S0EkUGcP3rYqZe+HdvyXD0+SR1f_3xWpu5FprKWuGhQ@mail.gmail.com>
.sdrawkcab esra s'ti ,tsop pot t'noD
(Don't top post, it's arse backwards.)
On Thu, Feb 02, 2012 at 04:17:02PM +0800, TAO HU wrote:
> My concern is not actually that the softlockup could not be reported
> while the IRQ is disabled.
> What bothering me is that even AFTER re-enable the IRQ, it will not
> give warning in many cases.
That's already been explained.
softlockups are detected by time passing. Time can't properly advance
with interrupts disabled, as the backing counter (assuming you're using
the clocksource and clockevent stuff) could wrap. If it wraps, the
systems idea of time which has passed will be incorrect.
So, if interrupts are disabled for a long period, the system loses track
of time, and therefore can't know how long the system has been blocked for.
next prev parent reply other threads:[~2012-02-02 8:44 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-31 7:28 In many cases softlockup can not be reported after disabling IRQ for long time TAO HU
2012-01-31 15:47 ` Don Zickus
2012-02-01 2:18 ` TAO HU
2012-02-01 10:51 ` Cong Wang
2012-02-01 14:58 ` Don Zickus
2012-02-02 8:17 ` TAO HU
2012-02-02 8:43 ` Russell King - ARM Linux [this message]
[not found] ` <CAOwKts--CDpmiMunfYKrYsnWovmQhAC7Vp0P-9MeNVy6vx-Wvw@mail.gmail.com>
2012-02-04 12:22 ` Russell King - ARM Linux
2012-02-02 15:58 ` Don Zickus
2012-02-02 16:22 ` Russell King - ARM Linux
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120202084350.GB1275@n2100.arm.linux.org.uk \
--to=linux@arm.linux.org.uk \
--cc=dzickus@redhat.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-omap@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=tghk48@motorola.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).