From: Frederic Weisbecker <fweisbec@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, hpa@zytor.com,
paulmck@linux.vnet.ibm.com, akpm@linux-foundation.org,
khilman@linaro.org, tglx@linutronix.de, axboe@fb.com,
linux-tip-commits@vger.kernel.org
Subject: Re: [tip:timers/nohz] nohz: Move full nohz kick to its own IPI
Date: Mon, 5 May 2014 17:34:08 +0200 [thread overview]
Message-ID: <20140505153405.GD2099@localhost.localdomain> (raw)
In-Reply-To: <20140505151228.GR26782@laptop.programming.kicks-ass.net>
On Mon, May 05, 2014 at 05:12:28PM +0200, Peter Zijlstra wrote:
> > Note the current ordering:
> >
> > cmpxchg(&qsd->pending, 0, 1) get ipi
> > csd_lock(qsd->csd) xchg(&qsd->pending, 1)
> > send ipi csd_unlock(qsd->csd)
> >
> >
> > So there shouldn't be racing updaters. Also ipi sender shouldn't
> > race with ipi receiver, the update shouldn't always eventually see
> > the unlock happening.
>
> Yeah, I've not spotted how this particular train wreck happens either.
>
> The problem is reproduction, it took me 9 hours to confirm I could
> reproduce the problem on my machine. So how long to I run it with this
> patch reverted to show its gone..
Maybe it could be favoured cpu hotplug. Anyway converting to irq_work should
fix it.
next prev parent reply other threads:[~2014-05-05 15:34 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <tip-72aacf0259bb7d53b7a3b5b2f7bf982acaa52b61@git.kernel.org>
2014-05-05 12:37 ` [tip:timers/nohz] nohz: Move full nohz kick to its own IPI Peter Zijlstra
2014-05-05 13:31 ` Peter Zijlstra
2014-05-05 15:04 ` Frederic Weisbecker
2014-05-05 15:12 ` Peter Zijlstra
2014-05-05 15:34 ` Frederic Weisbecker [this message]
2014-05-07 15:17 ` Peter Zijlstra
2014-05-07 15:29 ` Frederic Weisbecker
2014-05-07 15:37 ` Peter Zijlstra
2014-05-07 16:05 ` Frederic Weisbecker
2014-05-07 16:13 ` Peter Zijlstra
2014-05-07 19:07 ` Ingo Molnar
2014-05-09 15:10 ` Frederic Weisbecker
2014-05-11 5:34 ` Ingo Molnar
2014-05-05 14:52 ` Frederic Weisbecker
2014-05-05 14:58 ` Peter Zijlstra
2014-05-05 15:06 ` Frederic Weisbecker
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=20140505153405.GD2099@localhost.localdomain \
--to=fweisbec@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=axboe@fb.com \
--cc=hpa@zytor.com \
--cc=khilman@linaro.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=paulmck@linux.vnet.ibm.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.