[PATCH 0/2] nvme-fabrics: short-circuit connect retries

[Hannes Reinecke]

On 6/24/21 9:29 AM, Chao Leng wrote:
> 
> 
> On 2021/6/24 13:51, Hannes Reinecke wrote:
>> On 6/23/21 11:38 PM, Sagi Grimberg wrote:
>>>
>>>> Hi all,
>>>>
>>>> commit f25f8ef70ce2 ("nvme-fc: short-circuit reconnect retries")
>>>> allowed the fc transport to honour the DNR bit during reconnect
>>>> retries, allowing to speed up error recovery.
>>>
>>> How does this speed up error recovery?
>>
>> Well, not exactly error recovery (as there is nothing to recover).
>> But we won't attempt pointless retries, thereby reducing the noise in
>> the message log.
> This conflict with the tcp and rdma target.
> You may need to delete the improper NVME_SC_DNR at the target.
> However, this will cause compatibility issues between different versions.

Which ones?
I checked the DNR usage in the target code, and they seem to set it
correctly (ie the result would not change when the command is retried).
With the possible exception of ENOSPC handling, as this is arguably
dynamic and might change with a retry.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		           Kernel Storage Architect
hare at suse.de			                  +49 911 74053 688
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