From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Rich Felker <dalias@libc.org>
Cc: linux-kernel@vger.kernel.org, john.stultz@linaro.org, tglx@linutronix.de
Subject: Re: rcu_sched stalls in idle task introduced in pre-4.8?
Date: Wed, 3 Aug 2016 09:16:31 -0700 [thread overview]
Message-ID: <20160803161631.GA20790@linux.vnet.ibm.com> (raw)
In-Reply-To: <20160802204504.GL3482@linux.vnet.ibm.com>
On Tue, Aug 02, 2016 at 01:45:04PM -0700, Paul E. McKenney wrote:
> On Tue, Aug 02, 2016 at 04:32:17PM -0400, Rich Felker wrote:
> > On Tue, Aug 02, 2016 at 12:48:02PM -0700, Paul E. McKenney wrote:
[ . . . ]
> > > Does the problem reproduces easily?
> >
> > Yes, it happens right after boot and repeats every 30-90 seconds or
> > so.
>
> Well, that at least makes it easier to test any patches!
>
> > > A bisection might be very helpful.
> >
> > Bisection would require some manual work to setup because the whole
> > reason I was rebasing on Linus's tree was to adapt the drivers to
> > upstream infrastructure changes (the new cpuhp stuff replacing
> > notifier for cpu starting). The unfortunate way it was done, each
> > driver adds an enum to linux/cpuhotplug.h so all the patches have
> > gratuitous conflicts. In addition, for older revisions in Linus's
> > tree, there's at least one show-stopping (hang during boot) bug that
> > needs a cherry-pick to fix. There may be other small issues too. I
> > don't think they're at all insurmountible but it requires an annoying
> > amount of scripting.
>
> I had to ask! Might eventually be necessary, but let's see what we
> can learn from what you currently have.
And at first glance, my overnight run looks uglier than I would expect.
I am now running tests at v4.7, and will run other tests to see if
there really is a statistically significant degradation. If there is,
then I might be able to bisect, though with nine-hour runs this could
take quite some time.
Thanx, Paul
next prev parent reply other threads:[~2016-08-04 14:15 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-02 17:04 rcu_sched stalls in idle task introduced in pre-4.8? Rich Felker
2016-08-02 18:16 ` Paul E. McKenney
2016-08-02 19:20 ` Rich Felker
2016-08-02 19:48 ` Paul E. McKenney
2016-08-02 20:32 ` Rich Felker
2016-08-02 20:45 ` Paul E. McKenney
2016-08-03 16:16 ` Paul E. McKenney [this message]
2016-09-08 22:16 ` Rich Felker
2016-09-10 10:19 ` Paul E. McKenney
2016-09-12 15:13 ` Rich Felker
2016-09-12 15:36 ` Paul E. McKenney
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