On Tue, Oct 19, 2021 at 08:29:19AM +0200, Gerd Hoffmann wrote: > Hi, > > > > Yes. Maybe ask rh qe to run the patch set through their hotplug test > > > suite (to avoid a apci-hotplug style disaster where qe found various > > > issues after release)? > > > > I'll poke around to see if they can help us... we'll need > > a backport for that though. > > Easy, it's a clean cherry-pick for 6.1, scratch build is on the way. > > > > > I would also like to see a shorter timeout, maybe 100ms, so > > > > that we are more responsive to guest changes in resending request. > > > > > > I don't think it is a good idea to go for a shorter timeout given that > > > the 5 seconds are in the specs and we want avoid a resent request being > > > interpreted as cancel. > > > It also wouldn't change anything at least for linux guests because linux > > > is waiting those 5 seconds (with power indicator in blinking state). > > > Only the reason for refusing 'device_del' changes from "5 secs not over > > > yet" to "guest is busy processing the hotplug request". > > > > First 5 seconds yes. But the retries afterwards? > > Hmm, maybe, but I'd tend to keep it simple and go for 5 secs no matter > what. If the guest isn't responding (maybe because it is in the middle > of a reboot) it's unlikely that fast re-requests are fundamentally > changing things. > > > > We could consider to tackle the 5sec timeout on the guest side, i.e. > > > have linux skip the 5sec wait in case the root port is virtual (should > > > be easy to figure by checking the pci id). > > > > > > take care, > > > Gerd > > > > Yes ... do we want to control how long it blinks from hypervisor side? > > Is there a good reason for that? > If not, then no. Keep it simple. > > When the guest powers off the slot pcie_cap_slot_write_config() will > happily unplug the device without additional checks (no check whenever > the 5 seconds are over, also no check whenever there is a pending unplug > request in the first place). > > So in theory the guest turning off slot power quickly should work just > fine and speed up the unplug process in the common case (guest is > up'n'running and responsitive). Down to 1-2 secs instead of 5-7. > Didn't actually test that though. > > take care, > Gerd
Even if this speeds up unplug, hotplug remains slow, right? -- MST
