On Tue, 11 Apr 2017 16:12:11 -0500 Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > Hi Bodong, > > On Wed, Mar 22, 2017 at 05:53:58PM +0200, bodong@xxxxxxxxxxxx wrote: > > From: Bodong Wang <bodong@xxxxxxxxxxxx> > > > > 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? Logically it's similar, but the above is racy, not only would userspace need to serialize such operations but a device hot added during that blackout period wouldn't be probed. So this is like a per PF drivers_autoprobe for the VFs hosted by that device. Thanks, Alex > > Note that, the choice must be made before enabling VFs. The change > > will not take effect if VFs are already enabled. Simply, one can set > > sriov_numvfs to 0, choose whether to probe or not, and then resume > > sriov_numvfs. > > > > Signed-off-by: Bodong Wang <bodong@xxxxxxxxxxxx> > > Signed-off-by: Eli Cohen <eli@xxxxxxxxxxxx> > > Reviewed-by: Gavin Shan <gwshan@xxxxxxxxxxxxxxxxxx>
