[Jackit-devel] Re: [linux-audio-dev] Re: [Jackit-devel]2.4.20Â + lowlat +preempt + alsa + jack = dead computer

[Andrew Morton]

Fernando Pablo Lopez-Lezcano wrote:
> 
> ...
> 4)
> schedule +1ab
> sleep_on +45
> bread +20
> __mark_inode_dirty +d9
> pipe_write +1b9
> poll_freewait +44
> sys_write +9f
> system_call +33
> 
> So the system seems to be stuck in __mark_inode_dirty, whatever that is.

No, that's just stack gunk.

There's no sign of a deadlock or a livelock in these traces.  It just
looks like these tasks are asleep and not waking up.

> Each time I break into the debugger I see one of the jack related
> processes as the current process. No other processes, so I assume the
> SCHED_FIFO ring is still running but everything else is being blocked by
> the mark_inode_dirty call.

Why do we not believe that this is an application bug?   If the
SCHED_FIFO application is stuck in a loop, dead box.  And if "jack"
is always the running process, that appears to be the case.

Try running jack without SCHED_FIFO.

Give yourself a SCHED_FIFO shell (hiher priority than jack) so
that you can still poke around and run ps and things.  See if
`jack' is consuming 100% of CPU.  There's a little proggy called
`run_rr' in http://www.zip.com.au/~akpm/linux/zc.tar.gz which
will give you a SCHED_RR shell.