Re: [PATCH 0/5] scsi: Allow fast io fail without waiting through timeout

[Ren Mingxin <renmx@cn.fujitsu.com>]

Hi, James,

On 05/20/2013 11:53 PM, James Smart wrote:
> Based on the discussion recently held at LSF 2013, we are
> reworking the error recovery path to address all the issues
> you are mentioning. That work contradicts these patches.
> So for now, these should be held off.

Interesting. Can I have your general goal/idea briefly even
though via a reference? Will the URL below be one you will
refer to?
   http://lwn.net/Articles/548500

And, could I know your current progress/schedule? Especially
when can we see your patches?

Much appreciated!

Thanks,
Ren

>
> On 5/20/2013 3:14 AM, Ren Mingxin wrote:
>> When there is a scsi command timed-out or failed, the scsi eh
>> tries a thorugh recovery, which is necessary for non-redundant
>> systems. However, the thorugh recovery usually takes much time,
>> which is not acceptable for misson critical systems. To improve
>> this latency, if we are working on a redundant system, we should
>> avoid the scsi eh for its long time failing recovery, and quick
>> failover to another path.
>>
>> This set of patches is trying to implement above.
>>
>> NOTE: the userland tools need to eusure the environment
>> restriction, which will be implemented later.
>>
>> Thanks,
>> Ren
>>
>> Ren Mingxin (5):
>>    scsi: rename return code FAST_IO_FAIL to FAST_IO
>>    FC transport: Add interface to specify fast io level for timed-out 
>> cmds
>>    SAS transport: Add interface to specify fast io level for 
>> timed-out cmds
>>    lpfc: Allow fast timed-out io recovery
>>    mptfusion: Allow fast timed-out io recovery
>>
>>   drivers/message/fusion/mptscsih.c   |   29 ++++++++-
>>   drivers/scsi/lpfc/lpfc_scsi.c       |   34 ++++++++++
>>   drivers/scsi/scsi_error.c           |   18 ++---
>>   drivers/scsi/scsi_sas_internal.h    |    4 -
>>   drivers/scsi/scsi_transport_fc.c    |  112 
>> ++++++++++++++++++++++++++++++++++--
>>   drivers/scsi/scsi_transport_iscsi.c |    6 -
>>   drivers/scsi/scsi_transport_sas.c   |  103 
>> ++++++++++++++++++++++++++++++++-
>>   include/scsi/scsi.h                 |    2
>>   include/scsi/scsi_transport_fc.h    |   11 +++
>>   include/scsi/scsi_transport_sas.h   |    8 ++
>>   10 files changed, 303 insertions(+), 24 deletions(-)