Messages in this thread | | | Date | Wed, 3 Aug 2016 09:16:31 -0700 | From | "Paul E. McKenney" <> | Subject | Re: rcu_sched stalls in idle task introduced in pre-4.8? |
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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
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