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. :) Thanks
