[PARPORT] parport irq handler test w/ 3 devices

Boszormenyi Zoltan (zboszor@mol.hu)
Wed, 2 Sep 1998 08:29:22 +0100

Hello everyone!

As the discussion calmed down, I downloaded the 5th ( final? :) )
version of the parport-arca diff on an unmodified 2.1.119 and
tested a bit.

First, I have to make clear that I was unable to find a parameter
to explicitly tell pd or ppa to use interrupt, so it may turn out
that their drivers were actually polling the devices. I suspect this
because the responsiveness of my Linux box wasn't better than with
the unmodified kernel. It is noticable when the PHd is in action,
even changing VTs are very slow when I use it. PHd is a very slow,
nibble mode device, it would help a lot if it was able to use an
interrupt. I use "options pd nice=1 drive0=0x378,,,,,,0"
in /etc/conf.modules to make it a bit faster. In fact, this way
it is ~1.5x faster than with its DOS driver. :)

I did the following testing procedure:

I have a large (~5MB) ARJ archive file, copied to a device and unarj'd
back from that device or copied back to the hard drive and unarj'd there.
I did both way just for sure.

I trust arj and unarj because in the case of a corrupted archive they can
tell which file was corrupted in the archive and save the others.

Once I copyied the file, I unmounted/remounted the device to make sure that
when I read the file I get it from the device, not from the cache.

When I say "copying to ZIP/PHd" it means copying from the hard disk to
the mentioned device and the same applies to the opposite direction.

1. Single device tests
- printing
- copying to/from my ZIP or PHd drive
All went OK, no messages.

2. Two-device tests
- copying to/from my ZIP and PHd at the same time,
  four combinations in total: all were OK, no messages
- printing and copying to the PHd:
  "parport0: irq7 happened with irq_func NULL with pda as cad"
  message appeared ~10 times. While reading back the file I got the
  same message some times and once I got the
  "parport0: irq7 happened with port->cad NULL" message.
  The archive file was intact, there was no data loss.
- printing and copying to the ZIP:
  I got the same message:
  "parport0: irq7 happened with irq_func NULL with ppa as cad"
  once while copying the file, and once while umounting the ZIP.
  While reading back the file I got the above message twice and once this:
  "parport0: irq7 happened with port->cad NULL"
  Again, no data loss.

3. Three-device tests

- printing and copying to/from the ZIP and the PHd at the same time.
  - same data direction (both the ZIP and PHd were writing or both were
    reading): the messages mentioned only the pda driver or cad = NULL
  - opposite data direction: the messages mentioned the device that I read
    from. E.g.: copying to PHd and from ZIP at the same time I got
    "parport0: irq7 happened with irq_func NULL with ppa as cad" and
    "parport0: irq7 happened with port->cad NULL"
    messages and vice versa.
  There was no data loss.

Thanks for the attention,
Zoltan Boszormenyi

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