Strange 'hangs' with RELENG_9

[Volodymyr Kostyrko]

László KÁROLYI wrote:
> Hello,
>
> Recently I updated my RELENG_8 to RELENG_9. Since then, the server hangs
> from time to time for 5 minutes. When I run a top in a remote terminal,
> I can see that it hangs so strong, that the clock hangs too. When it
> continues to run , the time continues from the when it 'hanged'. TCP
> connections are also dropped with timeout at that time. However, no
> kernel panic, and i can't see anything in the dmesg log too.

Obtaining kernel dump is the way to go. You can occasionally find that 
obtaining dump on world built with clang is much easier than on 
gcc-compiled one. I remember at least one such case with broken zfs 
directory when trying to read such directory result in process with no 
state on gcc-compiled world and result in imminent panic in zfs code on 
clang-compiled world. Remember to set dumpdev to something appropriate.

> /boot/loader.conf:
> zfs_load="YES"
> vfs.root.mountfrom="zfs:pool/root"
> vfs.zfs.vdev.max_pending="8"
> geom_raid_load="YES"
> hint.siisch.0.sata_rev=1
> hint.siisch.1.sata_rev=1
>
> /etc/sysctl.conf:
> vfs.zfs.l2arc_noprefetch=0

This has impact on performance. You sure you really need that one? Can 
you try without it?

> /etc/make.conf, the kernel was compiled with this settings:
> CPUTYPE?=athlon64

Compiling with clang you better turn that thing off.

-- 
Sphinx of black quartz judge my vow.