On Nov 8 14:57, Łukasz Gieryk wrote: > On Mon, Nov 08, 2021 at 09:25:58AM +0100, Klaus Jensen wrote: > > On Nov 5 15:04, Łukasz Gieryk wrote: > > > On Fri, Nov 05, 2021 at 09:46:28AM +0100, Łukasz Gieryk wrote: > > > > On Thu, Nov 04, 2021 at 04:48:43PM +0100, Łukasz Gieryk wrote: > > > > > On Wed, Nov 03, 2021 at 01:07:31PM +0100, Klaus Jensen wrote: > > > > > > On Oct 7 18:24, Lukasz Maniak wrote: > > > > > > > From: Łukasz Gieryk > > > > > > > > > > > > > > With two new properties (sriov_max_vi_per_vf, sriov_max_vq_per_vf) one > > > > > > > can configure the maximum number of virtual queues and interrupts > > > > > > > assignable to a single virtual device. The primary and secondary > > > > > > > controller capability structures are initialized accordingly. > > > > > > > > > > > > > > Since the number of available queues (interrupts) now varies between > > > > > > > VF/PF, BAR size calculation is also adjusted. > > > > > > > > > > > > > > > > > > > While this patch allows configuring the VQFRSM and VIFRSM fields, it > > > > > > implicitly sets VQFRT and VIFRT (i.e. by setting them to the product of > > > > > > sriov_max_vi_pervf and max_vfs). Which is just setting it to an upper > > > > > > bound and this removes a testable case for host software (e.g. > > > > > > requesting more flexible resources than what is currently available). > > > > > > > > > > > > This patch also requires that these parameters are set if sriov_max_vfs > > > > > > is. I think we can provide better defaults. > > > > > > > > > > > > > > > > Originally I considered more params, but ended up coding the simplest, > > > > > user-friendly solution, because I did not like the mess with so many > > > > > parameters, and the flexibility wasn't needed for my use cases. But I do > > > > > agree: others may need the flexibility. Case (FRT < max_vfs * FRSM) is > > > > > valid and resembles an actual device. > > > > > > > > > > > How about, > > > > > > > > > > > > 1. if only sriov_max_vfs is set, then all VFs get private resources > > > > > > equal to max_ioqpairs. Like before this patch. This limits the number > > > > > > of parameters required to get a basic setup going. > > > > > > > > > > > > 2. if sriov_v{q,i}_private is set (I suggested this parameter in patch > > > > > > 10), the difference between that and max_ioqpairs become flexible > > > > > > resources. Also, I'd be just fine with having sriov_v{q,i}_flexible > > > > > > instead and just make the difference become private resources. > > > > > > Potato/potato. > > > > > > > > > > > > a. in the absence of sriov_max_v{q,i}_per_vf, set them to the number > > > > > > of calculated flexible resources. > > > > > > > > > > > > This probably smells a bit like bikeshedding, but I think this gives > > > > > > more flexibility and better defaults, which helps with verifying host > > > > > > software. > > > > > > > > > > > > If we can't agree on this now, I suggest we could go ahead and merge the > > > > > > base functionality (i.e. private resources only) and ruminate some more > > > > > > about these parameters. > > > > > > > > > > The problem is that the spec allows VFs to support either only private, > > > > > or only flexible resources. > > > > > > > > > > At this point I have to admit, that since my use cases for > > > > > QEMU/Nvme/SRIOV require flexible resources, I haven’t paid much > > > > > attention to the case with VFs having private resources. So this SR/IOV > > > > > implementation doesn’t even support such case (max_vX_per_vf != 0). > > > > > > > > > > Let me summarize the possible config space, and how the current > > > > > parameters (could) map to these (interrupt-related ones omitted): > > > > > > > > > > Flexible resources not supported (not implemented): > > > > > - Private resources for PF = max_ioqpairs > > > > > - Private resources per VF = ? > > > > > - (error if flexible resources are configured) > > > > > > > > > > With flexible resources: > > > > > - VQPRT, private resources for PF = max_ioqpairs > > > > > - VQFRT, total flexible resources = max_vq_per_vf * num_vfs > > > > > - VQFRSM, maximum assignable per VF = max_vq_per_vf > > > > > - VQGRAN, granularity = #define constant > > > > > - (error if private resources per VF are configured) > > > > > > > > > > Since I don’t want to misunderstand your suggestion: could you provide a > > > > > similar map with your parameters, formulas, and explain how to determine > > > > > if flexible resources are active? I want to be sure we are on the > > > > > same page. > > > > > > > > > > > > > I’ve just re-read through my email and decided that some bits need > > > > clarification. > > > > > > > > This implementation supports the “Flexible”-resources-only flavor of > > > > SR/IOV, while the “Private” also could be supported. Some effort is > > > > required to support both, and I cannot afford that (at least I cannot > > > > commit today, neither the other Lukasz). > > > > > > > > While I’m ready to rework the Flexible config and prepare it to be > > > > extended later to handle the Private variant, the 2nd version of these > > > > patches will still support the Flexible flavor only. > > > > > > > > I will include appropriate TODO/open in the next cover letter. > > > > > > > > > > The summary of my thoughts, so far: > > > - I'm going to introduce sriov_v{q,i}_flexible and better defaults, > > > according to your suggestion (as far as I understand your intentions, > > > please correct me if I've missed something). > > > - The Private SR/IOV flavor, if it's ever implemented, could introduce > > > sriov_vq_private_per_vf. > > > - The updated formulas are listed below. > > > > > > Flexible resources not supported (not implemented): > > > - Private resources for PF = max_ioqpairs > > > - Private resources per VF = sriov_vq_private_per_vf > > > > I would just keep it simple and say, if sriov_v{q,i}_flexible is not > > set, then each VF gets max_ioqpairs private resources. > > > > Since you did request more tuning knobs for the Flexible variant, the > Private one should follow that and allow full configuration. A device > where PF.priv=64 and each VF.priv=4 makes sense, and I couldn’t > configure it if sriov_v{q,i}_flexible=0 enabled the Private mode. > It was just to simplify, I am just fine with having `sriov_vq_private_per_vf` :) > > > - (error if sriov_vq_flexible is set) > > > > > > With flexible resources: > > > - VQPRT, private resources for PF = max_ioqpairs - sriov_vq_flexible > > > - VQFRT, total flexible resources = sriov_vq_flexible (if set, or) > > > VQPRT * num_vfs > > > - VQFRSM, maximum assignable per VF = sriov_max_vq_per_vf (if set, or) > > > VQPRT > > > > You mean VQFRT here, right? > > > > VQPRT is right, and – in my opinion – makes a better default than VQFRT. > > E.g., configuring a device: > > (max_vfs=32, PF.priv=VQPRT=X, PF.flex_total=VQFRT=256) > > as (num_vfs=1, VF0.flex=256) doesn’t make much sense. Virtualization is > not needed in such case, and user should probably use PF directly. On > the other hand, VQPRT is probably tuned to offer most (if not all) of > the performance and functionality; thus serves as a sane default. > Alright. > > > - VQGRAN, granularity = #define constant > > > > Yeah, 1 seems pretty reasonable here. > > > > > - (error if sriov_vq_private_per_vf is set) > > > > > > Is this version acceptable? > > > > > > > Sounds good to me. The only one I am not too happy about is the default > > of VQPRT * num_vfs. (i.e. max_ioqpairs * num_vfs) when vq_flexible is > > not set. I think this is the case where we should default to private > > resources. If you don't want to work with private resources right now, > > can we instead have it bug out and complain that sriov_vq_flexible must > > be set? We can then later lift that restriction and implement private > > resources. > > I would prefer reserving sriov_v{q,i}_flexible=0 for now. That's my current > plan for V2. > Alright.