> From: Bruce Evans <b...@optusnet.com.au> > Sent: Tuesday, April 10, 2018 13:09 > > Here the bug is that UP FreeBSD VM hangs on reboot or power-off, and > > I'm sure this recent patch (which was committed by Jeff on Mar 26) caused > > this bug: > > r331561:Fix a bug introduced in r329612 that slowly invalidates all clean > > bufs. > > > > However, SMP VM with 2 or more CPUs doesn't hang on reboot/power-off > > according to our tests. > > Actually, r329612 is what causes this bug. I already did the bisection > to find almost this bug a couple of weeks ago. The hang occurs on amd64 > with 4 CPUs but not on amd64 with 8 CPUs or i386 with 4 or 8 CPUS. I > just checked that it occurs on i386 with 1 CPU. All on the same machine. > But r329611 doesn't hang for any of these cases.
So, it looks to me that: r329612 introduced a hang issue, so Jeff made r331561, trying to fix the issue, but it looks the issue is not completely fixed (at least for me). I didn't test r329612. We noticed our amd64 VM (which has a single CPU) hung . The VM kernel was built with yesterday's latest kernel code + the default GENERIC kernel config. However, using the same kernel binary, if we configure 2 or more CPUs to the VM, the VM doesn't hang on reboot. If I use the latest code but manually remove the changes made by r331561, the hang issue with our single-CPU VM will go away. I hope the info is helpful. > I still think there is an older bug, but now think it is related. I > only tested with SCHED_4BSD. For SCHED_4BSD, I suspect that the bug > is from pinning a thread to a CPU and then stopping that CPU. Pure > UP has no problems since pinning is null for it. SCHED_4BSD has especially > special handing for SMP (a separate runq for each CPU. I have been > modifying > SCHED_4BSD and the separate queues mostly get in the way). > > Bruce I always use the default GENERIC kernel options, so I guess I'm using SCHED_4BSD(?).. Thanks, -- Dexuan _______________________________________________ freebsd-bugs@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-bugs To unsubscribe, send any mail to "freebsd-bugs-unsubscr...@freebsd.org"
