[ofa-general] WinOF_2_0_5/SRP initiator: slow reads and eventually hangs

[Chris Worley]

On Wed, Sep 2, 2009 at 2:58 PM, Chris Worley<worleys at gmail.com> wrote:
> On Wed, Sep 2, 2009 at 2:00 PM, Bart Van Assche<bart.vanassche at gmail.com> wrote:
>> On Wed, Sep 2, 2009 at 9:53 PM, Chris Worley<worleys at gmail.com> wrote:
>>> On Wed, Sep 2, 2009 at 1:31 PM, Bart Van Assche<bart.vanassche at gmail.com> wrote:
>>>> On Tue, Sep 1, 2009 at 1:04 AM, Chris Worley<worleys at gmail.com> wrote:
>>>>> [ ... ]
>>>>> I've found a good kernel/scst mix to easily repeat this; I can get it
>>>>> to repeatedly hang w/ 8K block transfers running Ubuntu 9.04 w/ the
>>>>> 2.6.27-14-server kernel on _both_ target and initiator (i.e. no WinOF
>>>>> or OFED at all) and SCST rev 1062 on the target using one drive
>>>>> (performance is >600MB/s, >80K IOPS, on the 8KB block sizes being
>>>>> used).
>>>>> [ ... ]
>>>>
>>>> Is there a special reason why you are using the 2.6.27-14-server
>>>> kernel ? AFAIK the latest Ubuntu 9.04 kernel is 2.6.28-15-server.
>>>
>>> No special reason other than it didn't get upgraded w/ the rest of the
>>> distro... started w/ 8.10.
>
> I'm upgrading too, to 9.04.

I tried the 2.6.28-15-server kernel (along w/ the 9.04 upgrade), and
it does repeat the issue.

In trying to build a kernel w/ lockdep support as Vlad requested, my
lack of Debian knowledge shone through, and, although I believe I
followed all the instructions correctly, I'm not sure if I have a
2.6.28-15 or 2.6.28-10 kernel.  Anyway, the issue is still repeatable.

Whatever kernel that is, I have SRP hung currently.  What should I
look for in /proc/lockd*?

I don't think it's a kernel lock... I think it's a protocol lock, as I
can rmmod the target kernel modules (scst_vdisk, scst, and ib_srpt)
when the initiator gets in this state.

Thanks,

Chris
>
> Chris
>>>
>>> Do you think that kernel is better?
>>
>> I noticed this while trying to reproduce this issue. I have no opinion
>> yet about which of these two kernels is better. I'll downgrade the
>> Ubuntu kernel in my setup.
>>
>> Bart.
>>
>