Re: [PATCH 2.4.x] prevent emulated SCSI hosts from wasting DMA memory

[Christoph Hellwig <hch@infradead.org>]

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)
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