From: Christoph Hellwig <hch@infradead.org>
To: Dan Aloni <da-x@monatomic.org>
Cc: Luke-Jr <luke-jr@utopios.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2.4.x] prevent emulated SCSI hosts from wasting DMA memory
Date: Thu, 1 Dec 2005 11:36:10 +0000 [thread overview]
Message-ID: <20051201113610.GG3958@infradead.org> (raw)
In-Reply-To: <20051130210222.GA32431@localdomain>
On Wed, Nov 30, 2005 at 11:02:23PM +0200, Dan Aloni wrote:
> On Wed, Nov 30, 2005 at 07:33:47PM +0000, Luke-Jr wrote:
> > On Wednesday 30 November 2005 17:15, Dan Aloni wrote:
> > > Emulated scsi hosts don't do DMA, so don't unnecessarily increase
> > > the SCSI DMA pool.
> >
> > They don't? Recently I learned(?) that apparently using hdparm -d on the
> > old /dev/hdX device still worked/applied when using ide-scsi... or do
> > "emulated scsi hosts" refer to something else?
>
> Actually by 'do DMA' I meant use the scsi_malloc() interface - which
> is mostly used by low level drivers. The IDE drivers allocate their
> DMA memory outside the SCSI layer. iSCSI hosts for instance, don't
> need to cause unnecessary DMA allocations.
(1) there's no guranteee a driver setting ->emulated can't use scsi_malloc
(2) 2.4.x is very late in the cycle so there's just no point in putting this
in (and in 2.6.x scsi_malloc is gone fortunately)
next prev parent reply other threads:[~2005-12-01 11:36 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-30 17:15 [PATCH 2.4.x] prevent emulated SCSI hosts from wasting DMA memory Dan Aloni
2005-11-30 19:33 ` Luke-Jr
2005-11-30 21:02 ` Dan Aloni
2005-12-01 11:36 ` Christoph Hellwig [this message]
2005-12-01 15:39 ` Dan Aloni
2005-12-21 18:17 ` Marcelo Tosatti
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