Subject: Re: PCI IDE HD performance figures (lack of)?

From: Philip Blundell <[email-masked]>
Date: Thu, 01 Oct 1998 21:30:45 +0100

> BuffType=0(?), BuffSize=128KB, MaxMultSect=32, MultSect=off
> DblWordIO=no, maxPIO=2(fast), DMA=yes, maxDMA=2(fast)
> CurCHS=13446/15/63, CurSects=12706470, LBA=yes, LBAsects=12706470
> tDMA={min:120,rec:120}, DMA modes: mword0 mword1 *mword2
> IORDY=on/off, tPIO={min:240,w/IORDY:120}, PIO modes: mode3 mode4

You're still not using 32-bit I/O or multiple sector transfers.  I suspect the 
former will give you almost a 100% performance improvement if the bus is the 
bottleneck.

Have you tried to turn these on?

p.

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From: "Neil A. Carson" <[email-masked]>
Date: Fri, 2 Oct 1998 10:10:51 +0100 (BST)

To e frank,

(and brief as I'm still in Hon gKong now) we've found that with *BSD, the
PIO performance of StronARM sucks too. I thought this may have been kernel
overheads but mayeb not. Using UltraDMA with the Promise, we get around
10MB/sec at least,w hcih is pretty cool (went down to 8 recently for some
reason AFAIR). Using PIO, though, we are lucky to touch 4MB/sec, even
32-bit mode 4. This is wierd as my PCI doing PIO mode 4 32-bit can do
(SORRY-16 BIT!) can do 8 MB/sec or something like that. Certainly 6.5-7.

So the SA is half as fast as this. Why??? Going now to save the phone
bil...

	Neil

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From: Dave Gilbert <[email-masked]>
Date: Fri, 2 Oct 1998 18:17:15 +0100 (BST)

> (SORRY-16 BIT!) can do 8 MB/sec or something like that. Certainly 6.5-7.

Something wierd is happening here; Alpha's suffer from the same problem;
my 533MHz Alpha could only do about 2MB/s off the EIDE disc without DMA;
turn DMA on and you get around 6MB/s (off an old disc at that).

So its not just an ARM related problem.

Dave

 --------------------------------------------------------------------   
/ Dr. David Alan Gilbert      | Running Linux on Alpha(LX) |  Happy  \ 
\   gro.gilbert @ treblig.org |   & ARM(EBSA285,old Arc)   |  In Hex /
 \____________________________|___ http://www.treblig.demon.co.uk __/

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From: James Craig <[email-masked]>
Date: Fri, 2 Oct 1998 19:11:24 +0100 (BST)

> So its not just an ARM related problem.
*definately* not. It does exactly the same on my K6-233. The timings are
roughly the same on one of my drives - don't remember which one now, and I
haven't really got the time to mess about testing them all - but I get
broadly similar effects anyway.
--
James Craig <[email-masked]>
            <[email-masked]>

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From: Alan Cox <[email-masked]>
Date: Sun, 4 Oct 1998 14:22:45 +0100 (BST)

> turn DMA on and you get around 6MB/s (off an old disc at that).

Similar to a lot of PC figures. DMA mode is equivalent to the highest PIO
modes and many controllers only support those modes in DMA form. UDMA is
faster than PIO modes full stop
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From: Russell King - ARM Linux Admin <[email-masked]>
Date: Wed, 7 Oct 1998 22:23:23 +0100 (BST)

> faster than PIO modes full stop

Ok, for those of you who are interested...

I've managed to get 7.6MB/s through the EBSA285 with Promise Ultra33 interface
in what I think is UDMA mode 1.  (after hanging the interface several times).
I think that I have to send a SetFeatures command to the drive to tell it I
want to use UDMA mode 2 before it'll work.

Note that practically, you can't get more than 10MB/s sustained transfer from
the drive - read:

	http://www.freenix.fr/linux/HOWTO-vo/mini/Ultra-DMA
	http://www.quantum.com/src/whitepapers/ultraata/

for more information.
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