On Wed, 26 Jul 2017 09:16:23 +0100 Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> wrote: > On Tue, 25 Jul 2017 21:12:17 -0700 > "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx> wrote: > > > On Tue, Jul 25, 2017 at 09:02:33PM -0700, David Miller wrote: > > > From: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx> > > > Date: Tue, 25 Jul 2017 20:55:45 -0700 > > > > > > > On Tue, Jul 25, 2017 at 02:10:29PM -0700, David Miller wrote: > > > >> Just to report, turning softlockup back on fixes things for me on > > > >> sparc64 too. > > > > > > > > Very good! > > > > > > > >> The thing about softlockup is it runs an hrtimer, which seems to run > > > >> about every 4 seconds. > > > > > > > > I could see where that could shake things loose, but I am surprised that > > > > it would be needed. I ran a short run with CONFIG_SOFTLOCKUP_DETECTOR=y > > > > with no trouble, but I will be running a longer test later on. > > > > > > > >> So I wonder if this is a NO_HZ problem. > > > > > > > > Might be. My tests run with NO_HZ_FULL=n and NO_HZ_IDLE=y. What are > > > > you running? (Again, my symptoms are slightly different, so I might > > > > be seeing a different bug.) > > > > > > I run with NO_HZ_FULL=n and NO_HZ_IDLE=y, just like you. > > > > > > To clarify, the symptoms show up with SOFTLOCKUP_DETECTOR disabled. > > > > Same here -- but my failure case happens fairly rarely, so it will take > > some time to gain reasonable confidence that enabling SOFTLOCKUP_DETECTOR > > had effect. > > > > But you are right, might be interesting to try NO_HZ_PERIODIC=y > > or NO_HZ_FULL=y. So many possible tests, and so little time. ;-) > > > > Thanx, Paul > > > I'll be the headless chicken running around and trying as many tests > as I can fit in. Typical time to see the failure for us is sub 10 > minutes so we'll see how far we get. > > Make me a list to run if you like ;) > > NO_HZ_PERIODIC=y running now. By which I mean CONFIG_HZ_PERIODIC=y Anyhow, run for 40 minutes with out seeing a splat but my sanity check on the NO_FULL_HZ=n and NO_HZ_IDLE=y this morning took 20 minutes so I won't have much confidence until we are a few hours in on this. Anyhow, certainly looking like a promising direction for investigation! Jonathan > > Jonathan > > _______________________________________________ > linuxarm mailing list > linuxarm@xxxxxxxxxx > http://rnd-openeuler.huawei.com/mailman/listinfo/linuxarm -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
