Messages in this thread | | | Subject | Re: [v2] PCI: Add an option to control probing of VFs before enabling SR-IOV | From | Bodong Wang <> | Date | Wed, 12 Apr 2017 11:00:06 -0500 |
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On 4/12/2017 10:22 AM, Bjorn Helgaas wrote: > On Wed, Apr 12, 2017 at 09:37:22AM -0500, Bodong Wang wrote: >> On 4/11/2017 4:12 PM, Bjorn Helgaas wrote: >>> Hi Bodong, >>> >>> On Wed, Mar 22, 2017 at 05:53:58PM +0200, bodong@mellanox.com wrote: >>>> From: Bodong Wang <bodong@mellanox.com> >>>> >>>> Sometimes it is not desirable to probe the virtual functions after >>>> SRIOV is enabled. This can save host side resource usage by VF >>>> instances which would be eventually probed to VMs. >>>> >>>> Add a new PCI sysfs interface "sriov_probe_vfs" to control that >>> >from the PF, all current callers still retain the same functionality. >>>> To modify it, echo 0/n/N (disable probe) or 1/y/Y (enable probe) to >>>> >>>> /sys/bus/pci/devices/<DOMAIN:BUS:DEVICE.FUNCTION>/sriov_probe_vfs >>> Is this basically the same functionality as /sys/bus/pci/drivers_autoprobe, >>> but limited to a specific PF? I.e., could we accomplish the same thing >>> with the following? >>> >>> # echo 0 > /sys/bus/pci/devices/DDDD:BB:dd.f/sriov_numvfs >>> # echo 0 > /sys/bus/pci/drivers_autoprobe >>> # echo 2 > /sys/bus/pci/devices/DDDD:BB:dd.f/sriov_numvfs >>> # echo 1 > /sys/bus/pci/drivers_autoprobe >>> >>> If not, can you contrast the above with drivers_autoprobe? If we need >>> both, should they be named more similarly? >> Hi Bjorn, >> >> I agree with Alex about not using driver_autoprobe to achieve this. >> It will affect all pci related device once it's disabled(probably in >> a bad way). > Alex mooted the idea of a generic driver core knob for devices that > create child devices. That's intriguing. What other situations > besides SR-IOV do this? Maybe we could add a "drivers_autoprobe" > inside the directory of each device that's capable of having child > devices? This seems interesting to me as well. Not sure if USB driver is applicable or not. And, drivers_autoprobe might work for USB if it doesn't probe the sub-device as default like sriov. Worth to take a look. > If we continue with the current approach (instead of Alex's idea), > I propose that you: > > - Name your new knob "sriov_drivers_autoprobe" to be consistent with > other sriov sysfs files while also being parallel to > "drivers_autoprobe" > > - Update Documentation/ABI/testing/sysfs-bus-pci to document your > new knob > > - Update Documentation/ABI/... to document drivers_autoprobe Ack, will send v3.
Thanks,
Bodong
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