On Thu, Jan 28, 2021 at 06:07:36PM -0600, Alex G. wrote: > On 1/28/21 5:51 PM, Sinan Kaya wrote: > > On 1/28/2021 6:39 PM, Bjorn Helgaas wrote: > > > AFAICT, this thread petered out with no resolution. > > > > > > If the bandwidth change notifications are important to somebody, > > > please speak up, preferably with a patch that makes the notifications > > > disabled by default and adds a parameter to enable them (or some other > > > strategy that makes sense). > > > > > > I think these are potentially useful, so I don't really want to just > > > revert them, but if nobody thinks these are important enough to fix, > > > that's a possibility. > > > > Hide behind debug or expert option by default? or even mark it as BROKEN > > until someone fixes it? > > > Instead of making it a config option, wouldn't it be better as a kernel > parameter? People encountering this seem quite competent in passing kernel > arguments, so having a "pcie_bw_notification=off" would solve their > problems. I don't want people to have to discover a parameter to solve issues. If there's a parameter, notification should default to off, and people who want notification should supply a parameter to enable it. Same thing for the sysfs idea. I think we really just need to figure out what's going on. Then it should be clearer how to handle it. I'm not really in a position to debug the root cause since I don't have the hardware or the time. If nobody can figure out what's going on, I think we'll have to make it disabled by default. > As far as marking this as broken, I've seen no conclusive evidence of to > tell if its a sw bug or actual hardware problem. Could we have a sysfs to > disable this on a per-downstream-port basis? > > e.g. > echo 0 > /sys/bus/pci/devices/0000:00:04.0/bw_notification_enabled > > This probably won't be ideal if there are many devices downtraining their > links ad-hoc. At worst we'd have a way to silence those messages if we do > encounter such devices. > > Alex
