On 09/11/2020 15:02, Leon Romanovsky wrote: > On Mon, Nov 09, 2020 at 02:47:07PM +0200, Gal Pressman wrote: >> On 09/11/2020 14:32, Leon Romanovsky wrote: >>> On Mon, Nov 09, 2020 at 02:27:16PM +0200, Gal Pressman wrote: >>>> On 09/11/2020 13:55, Leon Romanovsky wrote: >>>>> On Mon, Nov 09, 2020 at 11:03:25AM +0200, Gal Pressman wrote: >>>>>> >>>>>> On 09/11/2020 7:09, Leon Romanovsky wrote: >>>>>>> On Sun, Nov 08, 2020 at 07:49:35PM -0400, Jason Gunthorpe wrote: >>>>>>>> On Sun, Nov 08, 2020 at 03:03:45PM +0200, Gal Pressman wrote: >>>>>>>>> On 05/11/2020 22:00, Jason Gunthorpe wrote: >>>>>>>>>> On Tue, Nov 03, 2020 at 05:45:26PM +0200, Gal Pressman wrote: >>>>>>>>>>> On 03/11/2020 16:22, Jason Gunthorpe wrote: >>>>>>>>>>>> On Tue, Nov 03, 2020 at 04:11:19PM +0200, Gal Pressman wrote: >>>>>>>>>>>>> On 03/11/2020 15:57, Leon Romanovsky wrote: >>>>>>>>>>>>>> On Tue, Nov 03, 2020 at 09:45:22AM -0400, Jason Gunthorpe wrote: >>>>>>>>>>>>>>> On Tue, Nov 03, 2020 at 03:26:27PM +0200, Gal Pressman wrote: >>>>>>>>>>>>>>>> Add the ability to query the device's bdf through rdma tool netlink >>>>>>>>>>>>>>>> command (in addition to the sysfs infra). >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> In case of virtual devices (rxe/siw), the netdev bdf will be shown. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Why? What is the use case? >>>>>>>>>>>>>> >>>>>>>>>>>>>> Right, and why isn't netdev (RDMA_NLDEV_ATTR_NDEV_NAME) enough? >>>>>>>>>>>>> >>>>>>>>>>>>> When taking system topology into consideration you need some way to pair the >>>>>>>>>>>>> ibdev and bdf, especially when working with multiple devices. >>>>>>>>>>>>> The netdev name doesn't exist on devices with no netdevs (IB, EFA). >>>>>>>>>>>> >>>>>>>>>>>> You are supposed to use sysfs >>>>>>>>>>>> >>>>>>>>>>>> /sys/class/infiniband/ibp0s9/device >>>>>>>>>>>> >>>>>>>>>>>> Should always be the physical device >>>>>>>>>>>> >>>>>>>>>>>>> Why rdma tool? Because it's more intuitive than sysfs. >>>>>>>>>>>> >>>>>>>>>>>> But we generally don't put this information into netlink BDF is just >>>>>>>>>>>> the start, you need all the other topology information to make sense >>>>>>>>>>>> of it, and all that is in sysfs only already >>>>>>>>>>> >>>>>>>>>>> As the commit message says, it's in addition to the device sysfs. >>>>>>>>>>> >>>>>>>>>>> Many (if not most) of the existing rdma netlink commands are duplicates of some >>>>>>>>>>> sysfs entries, but show it in a more "modern" way. >>>>>>>>>>> I'm not convinced that bdf should be treated differently. >>>>>>>>>> >>>>>>>>>> Why did you call it BDF anyhow? it has nothing to do with PCI BDF >>>>>>>>>> other than it happens to be the PDF for PCI devices. Netdev called >>>>>>>>>> this bus_info >>>>>>>>> >>>>>>>>> Are there non pci devices in the subsystem? >>>>>>>> >>>>>>>> Yes, HNS uses non-pci devices >>>>>>>> >>>>>>>>> I can rename to a more fitting name, will change to bus_info unless >>>>>>>>> someone has a better idea. >>>>>>>> >>>>>>>> The thing is, is is still useless. You have to consult sysfs to >>>>>>>> understand what bus it is scoped on to do anything further with >>>>>>>> it. Can't just assume it is PCI. >>>>>>> >>>>>>> Can anyone please remind me why are we doing it? >>>>>>> What problem do you solve here by adding new nldev attributes? >>>>>> >>>>>> https://lore.kernel.org/linux-rdma/0825e1bf-f913-d2c1-ad3f-35ba3d6b75ef@xxxxxxxxxx/ >>>>> >>>>> Thanks, but IMHO it doesn't answer on the question about the problem. >>>> >>>> For example, in an instance with multiple NICs and GPUs, it's common to examine >>>> the devices topology and distances, device bdfs are needed for that. >>>> >>>> Also, when analyzing dmesg logs the prints contain the ibdev name, which is not >>>> always enough when trying to debug the corresponding physical device. >>> >>> Gal, >>> >>> I'm asking which problem will solve new nldev and not why BDF is important. :) >> >> This patch follows the implementation of other fields in fill_dev_info() such as >> port index, fw version, node guid, sys image guid, node type, dev protocol, etc, >> which also exist in sysfs. >> >> You added most of these new nldevs not long ago, so I find your question a bit >> confusing.. Can you please explain your concerns and why you think bdf is different? > > Almost all fields that you mentioned were needed to implement rdma_rename > utility that followed systemd internal implementation and/or were used in > the rdma-core. > > The FW version is clearly an exemption to the above. > > So I'm trying to understand the rationale behind BDF and how it will > work with different bus variants that we will have. Like Parav said, > the IB is connected to auxiliary bus (no BDF) and will have parent > with BDF too at the same time. We can review the different cases and make sure it works as expected (and what's expected), but let's first reach an agreement if I should continue with this work or not.
