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Date:      Mon, 29 Mar 2010 12:07:51 +0200
From:      Harald Schmalzbauer <h.schmalzbauer@omnilan.de>
To:        Alexander Motin <mav@FreeBSD.org>
Cc:        freebsd-stable@FreeBSD.org
Subject:   Re: ahcich timeouts, only with ahci, not with ataahci
Message-ID:  <4BB07BF7.6070602@omnilan.de>
In-Reply-To: <4B8E1B3D.306@FreeBSD.org>
References:  <1266934981.00222684.1266922202@10.7.7.3> <4B83EFD4.8050403@FreeBSD.org> <4B8E1489.2070306@omnilan.de> <4B8E1B3D.306@FreeBSD.org>

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Alexander Motin schrieb am 03.03.2010 09:18 (localtime):
> Harald Schmalzbauer wrote:
>> Alexander Motin schrieb am 23.02.2010 16:10 (localtime):
>>> Harald Schmalzbauer wrote:
>>>> I'm frequently getting my machine locked with ahcichX timeouts:
>>>> ahcich2: Timeout on slot 0
>>>> ahcich2: is 00000000 cs 00000001 ss 00000000 rs 00000001 tfd c0 serr=

>>>> 00000000
>>>> ahcich2: Timeout on slot 8
>>>> ahcich2: is 00000000 cs 00000100 ss 00000000 rs 00000100 tfd c0 serr=

>>>> 00000000
>>>> ahcich2: Timeout on slot 8
>>>> ahcich2: is 00000000 cs fffff07f ss ffffff7f rs ffffff7f tfd c0 serr=

>>>> 00000000
>>>> ...
>>> Looking that is (Interrupt status) is zero and `rs =3D=3D cs | ss` (r=
unning
>>> command bitmasks in driver and hardware), controller doesn't report
>>> command completion. Looking on TFD status 0xc0 with BUSY bit set, I
>>> would suppose that either disk stuck in command processing for some
>>> reason, or controller missed command completion status.
>>>
>>> Have you noticed 30 second (default ATA timeout) pause before timeout=

>>> message printed? Just want to be sure that driver waited enough befor=
e
>>> give up.
>>>
>>>> This happens when backup over GbE overloads ZFS/HDD capabilities.
>>>> I reduced vfs.zfs.txg.timeout to 1 to prevent the machine from locki=
ng
>>>> up almost immediately, but from it still happens.
>>>> When I don't use ahci but ataahci (the old driver if I understand th=
ings
>>>> correct) I also see the ZFS burst write congestion, but this doesn't=

>>>> lead to controller timeouts, thus blocking the machine.
>>>>
>>>> Sometimes the machine recovers from the disk lock, but most often I =
have
>>>> to reboot.
>>> How it looks when it doesn't? Can you send me full log messages?
>> Hello, this morning I had a stall, but the machine recovered after abo=
ut
>>  one Minute. Here's what I got from the kernel:
>> ahcich2: Timeout on slot 29
>> ahcich2: is 00000000 cs 00000003 ss e0000003 rs e0000003 tfd c0 serr
>> 00000000
>> em1: watchdog timeout -- resetting
>> em1: watchdog timeout -- resetting
>> ahcich2: Timeout on slot 10
>> ahcich2: is 00000000 cs 00006000 ss 00007c00 rs 00007c00 tfd c0 serr
>> 00000000
>> ahcich2: Timeout on slot 18
>> ahcich2: is 00000000 cs 00040000 ss 00000000 rs 00040000 tfd c0 serr
>> 00000000
>> ahcich2: Timeout on slot 2
>> ahcich2: is 00000000 cs 00000004 ss 00000000 rs 00000004 tfd c0 serr
>> 00000000
>> ahcich2: Timeout on slot 2
>> ahcich2: is 00000000 cs 00000000 ss 0000000c rs 0000000c tfd 40 serr
>> 00000000
>>
>> Does this tell you something useful?
>=20
> It doesn't. Looking on logged register content - commands are indeed
> still running and no interrupts requested. Interesting to see em1
> watchdog timeout there. Aren't they related somehow?

I have the drives now running in another server, ich7 chipset.
Using UFS, the complete machine locks up for ~30 secs with disk load of=20
3.5MB/s. But I don't get any timeout messages and the machine always=20
recovered.
Changing to the old ata driver solves the problem.
Any chance to get this problem fixed? I couldn't see lockups on another=20
OS with NCQ in AHCI mode enabled. I'd ship such a disk to anyone who is=20
willing to debug.

Thanks,

-Harry


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