[PATCH 1/4] nvme-tcp: per-controller I/O workqueues

[Hannes Reinecke]

On 7/3/24 16:11, Sagi Grimberg wrote:
> 
> 
> On 03/07/2024 16:50, Hannes Reinecke wrote:
>> Implement per-controller I/O workqueues to reduce workqueue contention
>> during I/O.
> 
> OK, wonder what is the cost here. Is it in ALL conditions better than a 
> single workqueue?

Well, clearly not on memory-limited systems; a workqueue per controller 
takes up more memory that a single one. And it's questionable whether
such a system isn't underprovisioned for nvme anyway.
We will see a higher scheduler interaction as the scheduler needs to 
switch between workqueues, but that was kinda the idea. And I doubt one
can measure it; the overhead between switching workqueues should be 
pretty much identical to the overhead switching between workqueue items.

I could do some measurements, but really I don't think it'll yield any
surprising results.

Cheers,

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