[5956] in linux-scsi channel archive
Re: proposal for big buffers under linux-scsi
daemon@ATHENA.MIT.EDU (Kurt Garloff)
Sun Feb 21 06:44:59 1999
Date: Sun, 21 Feb 1999 11:03:36 +0100
From: Kurt Garloff <K.Garloff@ping.de>
To: Gerard Roudier <groudier@club-internet.fr>,
linux-scsi@vger.rutgers.edu
Mail-Followup-To: Gerard Roudier <groudier@club-internet.fr>,
linux-scsi@vger.rutgers.edu
In-Reply-To: <Pine.LNX.3.95.990220224529.1568A-100000@localhost>; from Gerard Roudier on Sat, Feb 20, 1999 at 10:52:16PM +0100
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On Sat, Feb 20, 1999 at 10:52:16PM +0100, Gerard Roudier wrote:
> >=20
> > Latest linux scsi subsystem still tries to allocate huge physically
> > contiguous memory chunk. I know that large buffers are needed for devic=
es
> > as CD-R, scanners and friends, since Linus^Hx does not allow to DMA from
> > userland. However, allocating large physically contiguous buffers should
> > _never_ have been the solution, because it is only guaranteed to succeed
> > at system start-up and it is wasting memory to pool huge buffers when t=
hey
> > are not used.
> >=20
>=20
> I mentionned the mt driver in the post below and obviously meant 'st'
> instead. The st driver uses scatter lists since linux-2.1.121 and I
> just missed this improvement.
> Btw, the author of the st driver didn't miss my mistake. :)
But for the sg driver, needed for cdrecord and scanning, e.g., the problem
persists. There was a discussion about improvement of sg driver on this
list, a couple of weeks ago. Maybe you want to talk to Joerg Schilling=20
<schilling@fokus.gmd.de> about it.
--=20
Kurt Garloff <kurt@garloff.de> [Dortmund, FRG]
Plasma physics, high perf. computing [Linux-ix86,-axp, DUX]
PGP key: see mailheader [Linux SCSI driver: DC390]
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