On Fri, Aug 08, 2008 at 03:27:29PM +0100, David Woodhouse wrote:
quoted text
> On Fri, 2008-08-08 at 08:22 -0600, Matthew Wilcox wrote:
> > If the current T10 and T13 proposals stand unmodified, it'll be a bit of a
> > pain to implement fully.  PUNCH currently requires creating a data buffer
> > and attaching it to the command.  When we get down into libata, we then
> > want to throw that data buffer away again because TRIM doesn't need a
> > data buffer (indeed to translate PUNCH to TRIM, we need to send a series
> > of commands because PUNCH allows you to specify a set of ranges whereas
> > TRIM only lets you send one range at a time).
> > 
> > Let's hope T10 agrees that only one range is necessary at a time.
> 
> Weird. Does it really make sense for us to be 'translating' from generic
> requests to SCSI and then from those to ATA? I hadn't realised our code
> was that baroque...

We could do better by implementing an 'ata-drive' ULD for the scsi stack
that translated generic requests into ATA FIS's.  Possibly we could
do even better by moving ata out from inside the scsi stack entirely
... but that's already a kernelsummit discussion ;-)

-- 
Intel are signing my paycheques ... these opinions are still mine
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."
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