geom_raid5 livelock?

[R. B. Riddick]

--- CyberLeo Kitsana <cyberleo at cyberleo.net> wrote:
> Hence the testing. I wish to ensure there are as few problems as 
> possible when this is put into production.
>
OK... I understand that... Testing is important, but the programmer tends to
test not so good... ;-)

> The kernel does not panic, and everything resumes just fine as soon as 
> safeop is disabled. There are no new messages in the kernel log, nor in 
> syslog, and all disks are operating properly, if slowly (around 40 
> kilobytes per second each, with dd bs=4096).
>
Hmm - and at the same time u feel that the processes have to wait much longer
than necessary? Or is it possible, that the processes r just idle and read not
so often? What does "gstat" say (a screen shot during a suspected live lock
would be fine)? CPU usage according to "top"?

> Also, gcache doesn't seem to exist in the base system. Is this easier to 
> build than gjournal? (patching for that caused a whole ton of kernel and 
> world problems I'd rather not revisit)
>
Hmm - gcache is possibly only in 7-CURRENT...

> The attached list was taken during the most recent lockup.
> 
Looks perfect to me... :-)

You could try to activate graid5's debugging by setting the debug level to 2:
  sysctl kern.geom.raid5.debug=2
Then u should see the requests in /var/log/messages...
I would be interested then in those messages during a suspected live lock (just
wait for that strange condition and then set the debug level to 2 for some
seconds until u feel u have enough data...)...

-Arne


 
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