Re: [LSF/MM/BPF ATTEND][LSF/MM/BPF Topic] Non-block IO

[Hannes Reinecke <hare@suse.de>]

On 2/10/23 19:00, Kanchan Joshi wrote:
> is getting more common than it used to be.
> NVMe is no longer tied to block storage. Command sets in NVMe 2.0 spec
> opened an excellent way to present non-block interfaces to the Host. ZNS
> and KV came along with it, and some new command sets are emerging.
> 
> OTOH, Kernel IO advances historically centered around the block IO path.
> Passthrough IO path existed, but it stayed far from all the advances, be
> it new features or performance.
> 
> Current state & discussion points:
> ---------------------------------
> Status-quo changed in the recent past with the new passthrough path (ng
> char interface + io_uring command). Feature parity does not exist, but
> performance parity does.
> Adoption draws asks. I propose a session covering a few voices and
> finding a path-forward for some ideas too.
> 
> 1. Command cancellation: while NVMe mandatorily supports the abort
> command, we do not have a way to trigger that from user-space. There
> are ways to go about it (with or without the uring-cancel interface) but
> not without certain tradeoffs. It will be good to discuss the choices in
> person.
> 
I would love to have this discussion; that's something which has been on 
my personal to-do list for a long time, and io_uring might finally be a 
solution to it.

Or, alternatively, looking at CDL for NVMe; that would be an alternative 
approach.
Maybe it's even worthwhile to schedule a separate meeting for it.

Cheers,

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