Do you have a diff for your changes?  

I've tried to do something like this, but driver seemed to idnore all
but the first sector in the transfer.

--Artem

On Fri, Feb 27, 2004 at 05:51:43PM -0800, Ferry Sutanto <fsutanto@yahoo.com> wrote:
> Hi,
> 
> I made some changes to the ATA driver runs on SanDisk
> compact flash. SanDisk claim that it can read/write
> multiple sectors with single sector read/write
> command. In other words, the driver still issue single
> sector read/write command, but I set 'n' sectors in
> sector count register. I try it and it has been
> working wonderfully for 2 years now.
> 
> Thanks!
> 
> Ferry
> 
> --- Artem Belevich <art@riverstonenet.com> wrote:
> > Some time back I've whined about painfully slow I/O
> > on CompactFlash
> > cards in IDE mode. Looks like it could be improved.
> > 
> > To recap, under NetBSD/FreeBSD compactflash
> > operations are several
> > times slower than they are under Windows or Linux.
> > 
> > Recently I've spent some time tracking the problem
> > and it looks like
> > with some driver changes it would be possible to
> > speed it up.
> > 
> > The issue is that:
> > a) most CompactFlash cards claim to be capable of
> > 1-sector PIO0
> >    transfers only. I think it was a requirement in
> > the CF+ spec before
> >    rev1.4.
> > b) CF cards have fairly long command-to-DRQ delay.
> > One of Sandisk CF datasheets
> >    says that it can be up to ~1.2ms. My measurements
> > show the number pretty close 
> >    to that.
> > c) NetBSD driver issues a read command for *every*
> > sector.
> > 
> > Here's a timeline for reading a single sector during
> > 'dd bs=8192 count=<a lot>'.
> > 
> > 	     0   issue read command with sector count=1
> > 	+~1300us interrupt happens  (first command takes
> > long)
> > 	+~ 250us fetch the data from the disk
> > 
> >         while(have sectors to read){
> > 	    0	issue read command with sector count=1
> > 	+~300us interrupt happens
> > 	+~250us fetch the data from the disk
> > 
> > 	+  20us issue next command
> > 	}
> > 
> > All in all it's ~570us/sector or <1Mb/s.
> > 
> > I've experimented a bit with ATA drivers I've got
> > from
> > http://www.ata-atapi.com/drvr.htm and with the same
> > CF card I'm able
> > to achieve ~3.3Mb/s read rate compared to ~900K/s
> > I've got from the
> > same card with NetBSD.
> > 
> > The main difference between ata-atapi.com's code and
> > NetBSD is that
> > NetBSD issues read command with 1-sector count and
> > ata-atapi.com's
> > driver reads several sectors at a time (32 in my
> > case). 
> > 
> > The timings in this case looks like this:
> > 
> > 	     0   issue read command with sector count=N
> > 	+~1300us interrupt happens  (first command takes
> > long)
> > 	+~ 250us fetch the data from the disk
> > 
> > 	while (more sectors) {
> > 	         wait for next interrupt
> > 	+   11us interrupt happens  (*** only 11us until CF
> > delivers next sector.
> > 	+  250us fetch data
> > 	}
> > 
> > In this case it's ~260us/sector or ~2Mb/s.
> > 
> > So, if we could change NetBSD driver to issue single
> > read command for
> > N secors at a time, we'd be able to speed-up CF I/O
> > quite a bit.  
> > 
> > Note that I'm talking about regular read/write
> > commans (0x20/0x30),
> > not read-multiple/write-multiple commands
> > (0xc4/0xc5). I
> > 
> > Now, I'm not an expert on ATA/IDE and I'd appreciate
> > if someone more
> > familiar with the subject could take a look at the
> > issue at see if and
> > how it can be dealt with.
> > 
> > I wonder if the issue merits opening a PR for it.
> > 
> > --Artem
> > 
> > On Sun, Jul 14, 2002 at 07:26:00AM +0200, Wojciech
> > Puchar <wojtek@chylonia.3miasto.net> wrote:
> > > > Not the one(s) I have.
> > > >
> > > > wd1 at wdc0 channel 0 drive 0: <Hitachi
> > CVM1.3.3>
> > > > wd1: drive supports 1-sector PIO transfers, LBA
> > addressing
> > > > wd1: 244 MB, 695 cyl, 15 head, 48 sec, 512
> > bytes/sect x 500400 sectors
> > > >
> > > > So far all the CompactFlash cards I saw
> > (sandisk/lexar/io data/several
> > > > no-names) reported themselves as PIO 0 with
> > 1-sector-at-atime transfer
> > > > capability. :-( I believe, that's what one of
> > the earlier CF specs
> > > > insisted upon.
> > > >
> > > > I saw some references to the multisector-capable
> > CF cards on the web,
> > > > but I haven't seen any of them myself yet.
> > > 
> > > i think it's possible they really can multisector
> > but don't report. and
> > > with >1sec/s will be same 3000us delay
> > > 
> > > 
> > > >
> > > > --Artem
> > > >
> > > > On Sat, Jul 13, 2002 at 08:27:23AM +0200,
> > Wojciech Puchar <wojtek@chylonia.3miasto.net> wrote:
> > > > > > snapshot for both windows and NetBSD. This
> > should at least give us a
> > > > > > hint why are we so slow.
> > > > > >
> > > > > > What I see is that single-sector read
> > consists of
> > > > > >
> > > > > > 	command + 275us wait time + 150us data
> > transfer time = 430us.
> > > > > >
> > > > > > Write, on the other hand, looks a bit
> > different:
> > > > > > 	command+150us data transfer+2850us wait
> > time = 3000us
> > > > > >
> > > > > aren't these IDE-flash devices capable of IDE
> > multisector?
> > > > >
> > > >
> > > 
> > >
> >
> --------------------------------------------------------------------
> > > Charakterystycznymi cechami rozwoju oprogramowania
> > jest wyk?adniczy
> > > wzrost wymaga? sprz?towych, kwadratowy wzrost
> > ilo?ci b??d?w, liniowy
> > > wzrost ilo?ci bajer?w przy mniej ni? liniowym
> > wzro?cie funkcjonalno?ci
> > > 
> 
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