AHA-2940UW, DLT, alpha & aic driver

[Doug Ledford]

Metod Kozelj wrote:

> So you are suggesting that even if I actually read the data from DLT
> (using 'tar -tvf /dev/nst0'), it's just fine for stats not to reflect any
> reads? And that this is st driver's failure?

More like, the data length calculation can be done either A) quickly or B)
thoroughly.  As it turns out, I chose the quick method, which does rely upon
the upper SCSI driver layers to do the right thing, because this is in the
common code path and I didn't want to bear the overhead of checking the
command byte against too many possible alternatives.  However, as far as I
recall, the driver did previously record the data transfers on tape drives (it
didn't catch certain control ops, but actual reads and writes it did get). 
Are you sure that the performance stats stuff is turned on in the kernel
config?

-- 

 Doug Ledford <dledford at redhat.com>  http://people.redhat.com/dledford
      Please check my web site for aic7xxx updates/answers before
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