# Re: SG_BIG_BUFF, glibc 2.1 weirdness ...

Oliver Rauch (oliver.rauch@Wolfsburg.DE)
Sun, 15 Aug 1999 12:00:50 +0200

- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
- Next message: Oliver Rauch: "Re: SANE V2 - past discussions. A summary."
- Previous message: Petter Reinholdtsen: "SG_BIG_BUFF, glibc 2.1 weirdness ..."
- Maybe in reply to: Petter Reinholdtsen: "SG_BIG_BUFF, glibc 2.1 weirdness ..."
- Next in thread: Andreas Beck: "Re: SG_BIG_BUFF, glibc 2.1 weirdness ..."

Andreas Beck wrote:

> Hi folks. I just went almost mad tracking a very strange problem with sane
> 1.0.0, kernel 2.2.5 and glibc 2.1. I do not know, if it is fixed in 1.0.1.
> If so, please disregard this mail.

I run linux-2.2.5/x86 and sane-1.0.1 (SuSE-6.1)
after I changed the SG_BIG_BUFF to 128K in both sg.h files and recompiled the
kernel and sane everything works fine!

>
> O.K. - the problem is as follows:
>
> I wanted to increase SG_BIG_BUFF to get less scanner stops and thus increase
> throughput.
>
> Error #1: I had been told, that 256k were safe. This is correct, but only
> for Linux/alpha. The correct boundary is 32*PAGE_SIZE, wich is 4k*32=128k
> for Intel, but 8k*32=256k for Alpha.
>
> We should put that information in a README within SANE, not in the
> sg-readme, which is pretty obscure to find.

In the manpage sane-scsi there is written:
XX Unless a system is seriously
XX short on memory, it is recommended to increase this value
XX to the maximum legal value of 128*1024-512=130560 bytes.

> Now the big one that made me pull my hair:
>
> Glibc installs its _own_ scsi.h and sg.h, which are different from the
> kernel. Thus is you only edit sg.h from the Linux subdirectory you get very
> very weird behaviour:

This is something that should be changed in ther kernel surces/glic.

Bye
Oliver

    --
    EMAIL: Oliver.Rauch@Wolfsburg.DE
    WWW: http://www.wolfsburg.de/~rauch

    --
    Source code, list archive, and docs: http://www.mostang.com/sane/
    To unsubscribe: echo unsubscribe sane-devel | mail majordomo@mostang.com

     Next message: Oliver Rauch: "Re: SANE V2 - past discussions. A summary."
     Previous message: Petter Reinholdtsen: "SG_BIG_BUFF, glibc 2.1 weirdness ..."
     Maybe in reply to: Petter Reinholdtsen: "SG_BIG_BUFF, glibc 2.1 weirdness ..."

     Next in thread: Andreas Beck: "Re: SG_BIG_BUFF, glibc 2.1 weirdness ..."