On Tue, 13 Jun 2000, Stanley Wu wrote:
>There is definitely a need to specify different
>timeout values for different SCSI commands. For
...
I think there needs to be at least two independant timeouts. One for the
scsi core and one for the driver. Right now, I see command timeouts before
they were ever sent to the driver to be processed -- why should I reset the
scsi bus (read: fuck up the scsi subsystem) because the kernel failed to
post a command.
Timeouts are for the handling of exceptions -- basically a means to sense
that something is wrong. It's up to the driver to decide if the command
it has been asked to perform has actually failed or "timed out". The scsi
core needs a timer for application interfacing -- i.e. to signal EIO much
in the same fashion as an NFS fault if a command takes "too long."
This is not an easy problem to handle. Different devices and different
commands can have various execution times. Mix in RAID hardware and any
predictablity goes right out the window. Additionally, there needs to be
lock(s) for device and bus level resets -- all the scsi drivers need some
serious "reset logic" improvements. ... *sigh*
--Ricky
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