Hi Kevin,
On Thu, May 15, 2025 at 09:05:11PM -0700, Nicolin Chen wrote:
On Fri, May 16, 2025 at 03:52:16AM +0000, Tian, Kevin wrote:
But hey, we are already adding various restrictions to the uAPI about dependency, contiguity, etc. which the VMM should conform to. What hurts if we further say that the VMM should allocate virtual index in an ascending order along with hw queue allocation?
You mean adding another flag to manage the dependency in the core, right?
I talked with Jason offline when adding that depend API. He didn't want it to be in the core, saying that is a driver thing.
But that was before we added pin and contiguity, which he doesn't really enjoy being in the core either.
So, yea, I think you have a point here..
It seems Jason is out of office. And in the last sync w.r.t this, he thinks that this ascending order stuff is too unique/weird to make sense as a feature in the core, that there would be unlikely a second HW wanting this..
I think that's a valid point too. The pin/contiguity requirement at least serves for HW that reads in physical address space, and it could result in a slightly faster memory access since it does not need a translation, which though gives software some trouble yet still makes sense IMHO.
So, in v5, I kept the dependency APIs rather than moving to the core. I think we can move to the core later if we see another HW doing the same thing.
Thanks Nicolin