Re: Slow Disk I/O with QPS M3 80GB HD

[Ben Collins <bcollins@debian.org>]

On Tue, Dec 11, 2001 at 08:45:52AM -0800, H . J . Lu wrote:
> On Tue, Dec 11, 2001 at 11:05:07AM -0500, Ben Collins wrote:
> > On Mon, Dec 10, 2001 at 11:57:08PM -0800, H . J . Lu wrote:
> > > On Mon, Dec 10, 2001 at 08:34:52PM -0800, H . J . Lu wrote:
> > > > I have a very strange problem. The disk I/O of my QPS M3 80GB HD is
> > > > very slow under 2.4.10 and above. I got like 1.77 MB/s from hdparm.
> > > > But under 2.4.9, I got 14 MB/s on the same hardware. A 30GB HD has
> > > > consistent I/O performance under 2.4.9 and above on the same bus. Has
> > > > anyone else seen this? Does anyone have a large (>= 80GB) 1394 HD?
> > > > 
> > > 
> > > I did a binary search. 2.4.10-pre10 is the last good kernel. I got
> > > 
> > > # hdparm -t /dev/sda
> > > 
> > > /dev/sda:
> > >  Timing buffered disk reads:  64 MB in  4.40 seconds = 14.55 MB/sec
> > 
> > Have you checked the way that your ohci and sbp2 devices are detected
> > under each case? Most notably the max packet size.
> > 
> 
> They all say
> 
> ohci1394_0: OHCI-1394 1.0 (PCI): IRQ=[19]  MMIO=[f8ffd000-f8ffe000]  Max Packet=[1024]
> ieee1394: sbp2: SBP-2 device max speed S200 and payload 1KB

Have you tried linux1394 CVS with a 2.4.10pre10 kernel to narrow down
where the slowdown has occured?

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