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Date: Sat, 19 Jan 2002 13:44:17 -0800 (PST)
From: Davide Libenzi <davidel@xmailserver.org>
X-X-Sender: davide@blue1.dev.mcafeelabs.com
To: Andre Hedrick <andre@linuxdiskcert.org>
cc: Jens Axboe <axboe@suse.de>, Anton Altaparmakov <aia21@cam.ac.uk>,
        Linus Torvalds <torvalds@transmeta.com>,
        lkml <linux-kernel@vger.kernel.org>
Subject: Re: Linux 2.5.3-pre1-aia1
In-Reply-To: <Pine.LNX.4.10.10201191220060.7770-100000@master.linux-ide.org>
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On Sat, 19 Jan 2002, Andre Hedrick wrote:

> On Sat, 19 Jan 2002, Jens Axboe wrote:
>
> > On Sat, Jan 19 2002, Andre Hedrick wrote:
> > > On Sat, 19 Jan 2002, Jens Axboe wrote:
> > >
> > > > On Fri, Jan 18 2002, Davide Libenzi wrote:
> > > > > Guys, instead of requiring an -m8 to every user that is observing this
> > > > > problem, isn't it better that you limit it inside the driver until things
> > > > > gets fixed ?
> > > >
> > > > There is no -m8 limit, 2.5.3-pre1 + ata253p1-2 patch handles any set
> > > > multi mode value.
> > > >
> > > > --
> > > > Jens Axboe
> > > >
> > >
> > > And that will generate the [lost interrupt], and I have it fixed at all
> > > levels too now.
> >
> > How so? I don't see the problem.
>
> Unlike ATAPI which will generally send you more data than requested on
> itw own, ATA devices do not like enjoy or play the game.  Additionally the
> current code asks for 16 sectors, but we do not do the request copy
> anymore, and this mean for every 4k of paging we are soliciting for 8k.
> We only read out 4k thus the device has the the next 4k we may be wanting
> ready.  Look at it as a dirty prefetch, but eventally the drive is going
> to want to go south, thus [lost interrupt]
>
> Basically as the Block maintainer, you pointed out I am restricted to 4k
> chunking in PIO.  You decided, in the interest of the block glue layer
> into the driver, to force early end request per Linus's requirements to
> return back every 4k completed to block regardless of the size of the
> total data requested.
>
> For the above two condition to be properly satisfied, I have to adjust
> and apply one driver policy make the driver behave and give the desired
> results.  We should note this will conform with future IDEMA proposals
> being submitted to the T committees.

That was it. By limiting the sector count request i was able to fix it.
Do you've any permanent/not-hackish fix for this ?




- Davide


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