Re: 2.6.15-mm2

[Ric Wheeler <ric@emc.com>]

Reuben Farrelly wrote:

>
>
> On 13/01/2006 12:18 a.m., Tejun Heo wrote:
>
>> On Thu, Jan 12, 2006 at 09:38:48PM +1300, Reuben Farrelly wrote:
>> [--snip--]
>>
>>> [start_ordered       ] f7e8a708 -> c1b028fc,c1b029a4,c1b02a4c infl=1
>>> [start_ordered       ] f74b0e00 0 48869571 8 8 1 1 c1ba9000
>>> [start_ordered       ] BIO f74b0e00 48869571 4096
>>> [start_ordered       ] ordered=31 in_flight=1
>>> [blk_do_ordered      ] start_ordered f7e8a708->00000000
>>> [blk_do_ordered      ] seq=02 f74ccd98->f74ccd98
>>> [blk_do_ordered      ] seq=02 f74ccd98->f74ccd98
>>> [blk_do_ordered      ] seq=02 c1b028fc->00000000
>>> [blk_do_ordered      ] seq=02 c1b028fc->00000000
>>> [blk_do_ordered      ] seq=02 c1b028fc->00000000
>>
>>
>> Yeap, this one is the offending one.  0xf74ccd98 got requeued in front
>> of pre-flush while draining and when it finished it didn't complete
>> draining thus hanging the queue.  It seems like it's some kind of
>> special request which probably fails and got retried.  Are you using
>> SMART or something which issues special commands to drives?
>
>
> No SMART, although I should be (rebuilt the system a few months 
> ago..and must
> have missed it).
>
> Are there any other things which could be contributing to this?  
> <scratches head>
>
Could this be hdparm or something tweaking the drive write cache 
settings, etc?

ric