Re: CVS commit: src/sys/dev/scsipi

[Erik Fair <fair%netbsd.org@localhost>]

On Aug 9, 2013, at 12:58 , Frank Kardel <kardel%netbsd.org@localhost> wrote:

> Module Name:  src
> Committed By: kardel
> Date:         Fri Aug  9 19:58:44 UTC 2013
> 
> Modified Files:
>       src/sys/dev/scsipi: ch.c
> 
> Log Message:
> bump command timeout to 5 minutes. several
> types of changers (Overland PowerLoader, Dell
> PowerVault) have been exceeding the 100 sec
> limit aborting a perfectly (slowly) progressing
> operation.

Upon further reflection, I believe that this timeout value should be a 
device-specific tunable parameter because there is such wide variation in 
changer behavior/performance; perhaps by kernel config, or by sysctl(8) on a 
per-device-node basis. Or some other mechanism you prefer.

I believe that baking it into the kernel as a constant is not good design 
because we'll just see another commit just like this one at some later date, 
continuing to patch around the design problem.

        Erik <fair%netbsd.org@localhost>