[PATCH] nvmet: Set ctrl->kato to a default NVMET_DISC_KATO value

[Engel, Amit]

I was confused by the word "requires" which the spec uses (there is no "should" in the spec and "requires" sounds pretty strong):
NVMe-oF 1.1; 7.4.8 Keep Alive:
"...The NVMe/TCP Transport requires the use of the Keep Alive feature"

The same "requires" is also mentioned in RDMA:
NVMe-oF 1.1; 7.3.5 Keep Alive:
"...The RDMA Transport requires the use of the Keep Alive Feature"

Thanks for the clarification

-----Original Message-----
From: Linux-nvme <linux-nvme-bounces at lists.infradead.org> On Behalf Of Sagi Grimberg
Sent: Wednesday, August 19, 2020 6:24 PM
To: Engel, Amit; Christoph Hellwig
Cc: linux-nvme at lists.infradead.org
Subject: Re: [PATCH] nvmet: Set ctrl->kato to a default NVMET_DISC_KATO value


[EXTERNAL EMAIL] 


> Actually the spec says that NVME/TCP requires keep alive so it shouldn’t be 0.

Nothing in this language requires it. The keyword should means advice.

> Maybe we do need to set a default value in case of zero kato value ?

No, the patch is fine.

> NVMe-oF 1.1:
> 7.4.8 Keep Alive
> The NVMe/TCP Transport requires the use of the Keep Alive feature (refer to section 7.12 in the NVMe base specification). The NVMe/TCP Transport does not impose any limitations on the minimum and maximum Keep Alive Timeout value. The minimum should be set large enough to account for any transient fabric interconnect failures between the host and controller.
> TCP level Keep Alive functionality is not prohibited but it is recommended that TCP level Keep Alive timeout is set to a higher value than the NVMe Keep Alive Timeout to avoid conflicting policies.

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