taskqueue timeout

[Steve Bertrand]

Matthew Dillon wrote:

>     If you are getting DMA timeouts, go to this URL:

Yes, I am.

>     http://wiki.freebsd.org/JeremyChadwick/ATA_issues_and_troubleshooting

I fall under the category of "ATA/SATA DMA timeout issues".

>     Then I would suggest going into /usr/src/sys/dev/ata (I think, on
>     FreeBSD), locate all instances where request->timeout is set to 5,
>     and change them all to 10.
> 
> 	cd /usr/src/sys/dev/ata
> 	fgrep 'request->timeout' *.c
> 	... change all assignments of 5 to 10 ...
> 
>     Try that first.  If it helps then it is a known issue.  Basically
>     a combination of the on-disk write cache and possible ECC corrections,
>     remappings, or excessive remapped sectors can cause the drive to take
>     much longer then normal to complete a request.  The default 5-second
>     timeout is insufficient.
> 
>     If it does help, post confirmation to prod the FBsd developers to
>     change the timeouts.

I've just reproduced the problem, and will try hacking the code now to 
see if the problem goes away.

Since the box won't take input, I can't tell the disk usage at the time 
it dies. However, it seems to appear while running an Amanda backup, and 
my network throughput hits about ~90 Mbps @ ~5 kpps.

I'll post back with results of the increase of the timeout.

Steve