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To: =?ISO-8859-1?Q?S=F8ren_Schmidt?= <sos@DeepCore.dk>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Sat, 13 Nov 2004 11:29:19 +0100."
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Date: Sat, 13 Nov 2004 11:34:34 +0100
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cc: Garance A Drosihn <drosih@rpi.edu>
cc: Zoltan Frombach <tssajo@hotmail.com>
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cc: Robert Watson <rwatson@freebsd.org>
Subject: Re: 5.3-RELEASE: WARNING - WRITE_DMA interrupt timout 
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In message <4195E1FF.5090906@DeepCore.dk>, =?ISO-8859-1?Q?S=F8ren_Schmidt?= wri
tes:

>>>Timeout is 5 secs, which is a pretty long time in this context IMHO..
>> 
>> Five seconds counted from when ?
>
>Now thats the nasty part :)
>ATA starts the timeout when the request is issued to the device, so 
>theoretically the disk could take 4.9999 secs to complete the request 
>and then the timeout fires before the taskqueue gets its chance at it, 
>but IMHO thats pretty unlikely...

I find that far more likely than kernel threads being stalled for that
long.  ATA disks doing bad-block stuff takes several seconds on some
of the disks I've had my hands on.

>Anyhow, I can just remove the warning from ATA if that makes anyone 
>happy, since its just a warning and ATA doesn't do anything with it at all.
>However, IMNHO this points at a problem somewhere that we should better 
>understand and fix instead.

I would prefer you reset the timer to five seconds in your interrupt
routine so we can see exactly on which side of that the time is spent.


-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.