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Date:      Sat, 13 Nov 2004 11:00:30 +0100
From:      =?ISO-8859-1?Q?S=F8ren_Schmidt?= <sos@DeepCore.dk>
To:        Poul-Henning Kamp <phk@phk.freebsd.dk>
Cc:        Robert Watson <rwatson@freebsd.org>
Subject:   Re: 5.3-RELEASE: WARNING - WRITE_DMA interrupt timout
Message-ID:  <4195DB3E.2040807@DeepCore.dk>
In-Reply-To: <25539.1100339599@critter.freebsd.dk>
References:  <25539.1100339599@critter.freebsd.dk>

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Poul-Henning Kamp wrote:
> In message <4195D903.2090801@DeepCore.dk>, =3D?ISO-8859-1?Q?S=3DF8ren_S=
chmidt?=3D wri
> tes:
>=20
>>Zoltan Frombach wrote:
>>
>>>This is still an issue for me. Please read this post of mine:
>>>http://lists.freebsd.org/pipermail/freebsd-stable/2004-November/009420=
=2Ehtml
>>>
>>>Can anyone help? I would gladely install test patches to track this=20
>>>problem down. My system is 5.3-R. And the WRITE_DMA warning happens at=
=20
>>>least twice a day, it is so predictable. With thanks,
>>
>>Hmmm, that warning is issued from ATA when requests has been returned t=
o=20
>>the systems bio_taskqueue but the system hasn't finished them within th=
e=20
>>timeout. Now this is an indication of the system being unresponsive=20
>>already at that point, or at least that was the idea.
>>It has nothing to do with a bad drive, since the interrupt was seen the=
=20
>>drive has finished the request it was asked, its the layers above ATA=20
>>that doesn't respond to the request beeing returned as finished.
>=20
> It is not really the task of the ata driver to fail requests at that
> time.   How long is the timeout anyway ?

Oh, ATA doesn't fail them, it just yells that the request hasn't been=20
finished yet by the upper layers, it doesn't do anything to the request.

Timeout is 5 secs, which is a pretty long time in this context IMHO..

However, if it can take that long time to get data pushed up the chain,=20
it might also explain some of the reduced I/O performance reported ?

--=20

-S=F8ren




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