Re: TSTILE lockups on disk dump/backups

[Don Lee <MacPPC2%c.icompute.com@localhost>]

> On Dec 21, 2024, at 9:21 AM, Martin Husemann <martin%duskware.de@localhost> wrote:
> 
> On Sat, Dec 21, 2024 at 02:20:23AM -0600, Don Lee wrote:
>> Any thought about how I should deal with this? My kernel debugging
>> skills are weak. Is there anything I can do to produce useful debug
>> information next time this happens?
> 
> A tstile just means the process/kernel thread is blocked for a longer
> time waiting for "something". In this context that would typically be
> either a disk buffer ("buf") read from disk (the source you are backing
> up) or a network buffer ("mbuf") handed to the network device output
> queue.
> 
> This would point to a bug in the disk driver or the network driver.

Wherever it is, I didn’t see it on NetBSD 8.2. That may mean that it’s a new bug, or it might be that something in the timing of 8.2 just didn’t trigger it.

It’s a macppc system with 1 GB of memory. I wonder if NetBSD 9.4 needs more memory...

> The other option would be your system runing out of kernel address space,
> so it can not allocate either type of buffer. This would show up in 
> the output of vmstat -s (or you are running against limits for either
> type of buffer, but I would expect that to fail differently).

> Can you start new processes in the state when it hangs? Like the vmstat -s 
> mentioned above, or "crash" to look at kernel state? I am not sure "crash"
> would work on macppc and 9.x good enough.

> Martin

 I should be able to do a vmstat -s next time it hangs. It seems that most processes run OK while the system's stuck, as long as I don’t touch the the filesystem(s) the wrong way. If I don’t notice the hang, the dump processes “pile up” as they get launched by cron. Eventually, I can’t log in, but early in the process, I can log in and do stuff.

Many thanks,

-dgl-