[5821] in linux-scsi channel archive
Re: WG: AW: cdrecord problems on recent Linux versions
daemon@ATHENA.MIT.EDU (Joerg Schilling)
Tue Feb 9 07:54:30 1999
Date: Tue, 9 Feb 1999 13:48:58 +0100 (MET)
From: Joerg Schilling <schilling@fokus.gmd.de>
To: Dominik.Stadler@btk.de, heiko_eissfeldt@z.detesystem.de,
schilling@fokus.gmd.de, xiphmont@mit.edu
Cc: cdwrite@lists.debian.org, linux-scsi@vger.rutgers.edu
>From Dominik.Stadler@btk.de Mon Feb 8 18:40:41 1999
>As far as I understood it (Heiko, please correct me, if this isn't =
>correct),
>the sg_2_0_35.patch allocates one distinct buffer per SCSI-Device in =
>steps
>of exactly 32K, 64K, 128K and for more it allocates the amount needed.
>Every device has it's own buffer and tries to use it for the next =
>allocation
>if the size is big enough, otherwise the buffer is thrown away and a
>suitable bigger buffer is allocated.
The problem is that in order to do SCSI bus scanning cdrecord needs to
open all devices and the current algorithm does not free any of them in this
case.
>The intention was to part the allocation for the devices in contrast to =
>the
>earlier SG_BIG_BUF-Implementation where every device shared one buffer, =
>thus
>leading to problems with programs writing/reading concurrently on =
>different
>devices. But we would like to be able to burn CDs and read another in =
>the
>2nd CD-Device at one time.
>My error arises, because cdrecord opens ALL found SCSI-Devices, doing =
>the
>necessary inquiry and then close ALL devices again, thus needing 32K =
>for
>each found device. On the other hand, I don't know if 192K is really to =
>much
>memory to allocate with kmalloc() on my system? Anybody any =
>information?
The problem is that you need physically continuous memory for this operation
and this may fail.
Jörg
EMail:joerg@schily.isdn.cs.tu-berlin.de (home) Jörg Schilling D-13353 Berlin
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