FreeBSD 8.1-R/amd64 - zfs 'hangs' - help tracing?

[Karl Pielorz]

--On 29 September 2010 11:24 +0100 Martin Simmons <martin at lispworks.com> 
wrote:

>> I saw a while ago a command under 8.1 to get 'more info' for these stuck
>> processes, but can't for the life of me remember it?
>
> Maybe procstat -k -k $pid is what you are looking for (i.e. a kernel
> backtrace)?  Use -a instead of $pid to get all processes.

Yup, that's it - thanks!

Having run it I get:

procstat -k -k 1927 (PID 1927 is the 'ls' that's locked up)

  PID    TID COMM             TDNAME           KSTACK
 1927 100206 ls               -                mi_switch+0x16f 
sleepq_wait+0x42 _cv_wait+0x111 zio_wait+0x61 dbuf_read+0x39a 
dnode_hold_impl+0xe7 dmu_bonus_hold+0x2a zfs_zget+0x227 
zfs_dirent_lock+0x4e3 zfs_dirlook+0x69 zfs_lookup+0x1f0 
zfs_freebsd_lookup+0x81 vfs_cache_lookup+0xf0 VOP_LOOKUP_APV+0x40 
lookup+0x40a namei+0x52b kern_statat_vnhook+0x8f kern_statat+0x15


Which will hopefully mean something more to someone here than it does me at 
the moment ;)

-Karl