[sane-devel] [RFC, PATCH] Re: Bug#420193: libsane on sparc64 with SCSI scanner

[abel deuring]

Hi Julien,

Julien BLACHE wrote:
> abel deuring <adeuring at gmx.net> wrote:
> 
> Hi,
> 
>>> I think we can even get rid of the old SG interface entirely. SG_IO
>>> exists in Linux 2.4 too, so it should be safe.
>> I must admit that I am one of these persons who cannot throw away
>> anything... But you are right: Doug Gilbert wrote the SG3 interface in
>> the late 90ies (IIRC, the first versions were available even for 2.2.x
>> kernels), so keeping the old interface would be useful for very few
>> people, if any.
> 
> According to <http://sg.torque.net/sg/> SG3 was first released in a
> stable kernel with Linux 2.4.0 in 2001. It's unclear to me whether
> it's been available in Linux 2.2 before that. (are there really people
> here still running SANE on a 2.2 kernel ?)

It seems that my memory it not very well functioning ;) Perhaps there
were some some beta versions available earlier, but never mind.

> 
>>> The latency here seems low enough, and this machine is an SGI Indigo2
>>> R4400SC 200 MHz w/256 MB RAM and an asthmatic SCSI controller (under
>>> Linux, at least, because we don't have the specs ...)
>> The effects of longer latency times seem to depend heavily on the
>> scanner models. The Sharp JX250, a moderately fast model, probably with
>> only a tiny internal buffer, seems to suffer more than many other devices...
> 
> It'd be nice to gather some feedback on my patch with a couple of
> different scanners, that'd set the record straight as far as latency
> goes :)

It could be that the JX250 is much more sensistive to latency problems
than other scanners... I'll test your patch during the next days (sorry,
I can't make at present a more precise and honest promise...). But I
already made some test scans with sane-backends 1.0.18 and a modified
sharp.conf file that disables queueing on the SG level: No performance
problems with a 1.6 GHZ Athlon mainboard and a SCSI controller for the
sym53c8xx driver. (I don't have a slower system available...)

Abel