On Mon, Aug 22, 2016 at 4:30 PM, Kevin Oberman <rkober...@gmail.com> wrote:
> On Mon, Aug 22, 2016 at 12:54 PM, Jan Mikkelsen <j...@transactionware.com> > wrote: > >> Hi, >> >> On 23 Aug 2016, at 02:25, Kevin Oberman <rkober...@gmail.com> wrote: >> >> On Mon, Aug 22, 2016 at 1:50 AM, Jan Mikkelsen <j...@transactionware.com> >> wrote: >> >>> Do you have aio loaded or compiled into your kernel? If so, does it keep >>> happening without aio? >>> [ … ] >>> >> Thanks for the suggestion, but, no. This is on my trusty Lenovo T520 >> laptop and no aio to be found. My configuration is just: >> include GENERIC >> ident GENERIC_BSD4 >> >> nooptions SCHED_ULE # ULE scheduler >> options SCHED_4BSD # 4BSD scheduler >> >> I still can't be sure if the problem was triggered by the move to VB 5 or >> t FreeBSD-11 (or a combination of both). >> >> >> Yes, the problem could be in many places. However, if you’ve gone to >> FreeBSD 11, you have more aio than you think. From UPDATING: >> >> 20160301: >> The AIO subsystem is now a standard part of the kernel. The >> VFS_AIO kernel option and aio.ko kernel module have been removed. >> Due to stability concerns, asynchronous I/O requests are only >> permitted on sockets and raw disks by default. To enable >> asynchronous I/O requests on all file types, set the >> vfs.aio.enable_unsafe sysctl to a non-zero value. >> >> Are you running the VM against a raw disk device? You can check the >> VBox.log output — If you are not using aio, you should see an entry like >> this: >> >> AIO: Async I/O manager not supported (rc=VERR_NOT_SUPPORTED). Falling >> back to simple manager >> >> If you are using AIO, you will should see entries like: >> >> AIOMgr: Default manager type is "Async" >> AIOMgr: Default file backend is “NonBuffered" >> >> >> AIO issues were not a big issue for a long time but some recent updates >> to 4.3.something (or other environmental issues, possibly load) led me to >> turn aio off on a bunch of 10.x machines running a significant number of >> VMs (~25). I’m have been curious about whether the aio change would cause >> problems with an upgrade to 11. >> >> Regards, >> >> Jan. >> >> > BINGO! > > Thank you so much, Jan! This does explain a great deal of what I was > seeing and why. > > Now the question... how can I disable it? I'm guessing that > "kern.features.aio=0" in /boot/loader.conf might do the trick, but the man > page does not mention this at all. Also, I guess it is time to open a bug > report on this. FWIW, the problem does seem to be linked to disk activity. > I had the system locked up and had to kill the process. When I rebooted, > the system told me that a disk check was needed, but I had it lock up > several time (3, I think) before it made it through the check without > locking up again. Once that was complete, the system started and ran > normally again. This also now fits rather well with an aio issue. > > Not too sure how to go about collecting more information for the PR,but > I'll open it with what I have. > > Thanks again, Jan! > -- > Kevin Oberman, Retired Network Engineer > FYI, there is a PR on this. https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=168298 I have updated the ticket with what I have seen, especially that it is not ZFS specific. I have also made the adjustment in sysctls as shown in the ticket (comment 3) and will see how things works. -- Kevin Oberman, Retired Network Engineer E-mail: rkober...@gmail.com _______________________________________________ freebsd-emulation@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-emulation To unsubscribe, send any mail to "freebsd-emulation-unsubscr...@freebsd.org"
