From: Alex Williamson <firstname.lastname@example.org> To: Alex G <email@example.com> Cc: Bjorn Helgaas <firstname.lastname@example.org>, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, Shyam_Iyer@Dell.com, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org Subject: Re: [PATCH] PCI/LINK: Account for BW notification in vector calculation Date: Tue, 23 Apr 2019 12:38:28 -0600 [thread overview] Message-ID: <email@example.com> (raw) In-Reply-To: <firstname.lastname@example.org> On Tue, 23 Apr 2019 12:53:07 -0500 Alex G <email@example.com> wrote: > On 4/23/19 12:10 PM, Bjorn Helgaas wrote: > > On Tue, Apr 23, 2019 at 09:33:53AM -0500, Alex G wrote: > >> On 4/22/19 7:33 PM, Alex Williamson wrote: > >>> There is nothing wrong happening here that needs to fill logs. I > >>> thought maybe if I enabled notification of autonomous bandwidth > >>> changes that it might categorize these as something we could > >>> ignore, but it doesn't. How can we identify only cases where this > >>> is an erroneous/noteworthy situation? Thanks, > >> > >> You don't. Ethernet doesn't. USB doesn't. This logging behavior is > >> consistent with every other subsystem that deals with multi-speed links. > > > > Can you point me to the logging in these other subsystems so I can > > learn more about how they deal with this? > > I don't have any in-depth articles about the logging in these systems, > but I can extract some logs from my machines. > > Ethernet: > > [Sun Apr 21 11:14:06 2019] e1000e: eno1 NIC Link is Down > [Sun Apr 21 11:14:17 2019] e1000e: eno1 NIC Link is Up 1000 Mbps Full > Duplex, Flow Control: Rx/Tx > [Sun Apr 21 11:14:23 2019] e1000e: eno1 NIC Link is Up 1000 Mbps Full > Duplex, Flow Control: Rx/Tx > [Sun Apr 21 23:33:31 2019] e1000e: eno1 NIC Link is Down > [Sun Apr 21 23:33:43 2019] e1000e: eno1 NIC Link is Up 1000 Mbps Full > Duplex, Flow Control: Rx/Tx > [Sun Apr 21 23:33:48 2019] e1000e: eno1 NIC Link is Up 1000 Mbps Full > Duplex, Flow Control: Rx/Tx > > I used to have one of these "green" ethernet switches that went down to > 100mbps automatically. You can imagine how "clogged" the logs were with > link up messages. Thank goodness that switch was killed in a thunderstorm. > > USB will log every device insertion and removal, very verbosely (see > appendix A). I have a hard time putting USB insertion and removal into the same class, the equivalent is PCI hotplug which is logged separately. Do we ever log beyond USB device discovery if a device is running at a lower speed than is possible? The most directly related is the green ethernet switch, which you admit was a nuisance due to exactly this sort of logging. It was probably confusing to see this logging, perhaps you wondered if the cable was bad or the switch was defective. > > I agree that emitting log messages for normal and expected events will > > lead to user confusion and we need to do something. > > > > e8303bb7a75c ("PCI/LINK: Report degraded links via link bandwidth > > notification") was merged in v5.1-rc1, so we still have (a little) > > time to figure this out before v5.1. > > I always viewed the system log as a system log, instead of a database of > system errors. I may have extremist views, but going back to Alex's > example, I prefer to see that the power saving mechanism is doing > something to save power on my laptop (I'll just ignore it on a desktop). There's a disconnect from above where similar behavior on ethernet behavior "clogged" the log files, but here we just want to ignore it. Excessive logging can also be considered a denial of service vector when the device generating that excessive logging is attached to a userspace driver. > If you think increasing code complexity because people don't want things > logged into the system log, then I'm certain we can work out some sane > solution. It's the same problem we see with GCC, where people want > warning messages here, but don't want the same messages there. v5.1 is approaching quickly, can we downgrade these to pci_dbg() while we work on maybe some sort of driver participation in this logging? Thanks, Alex
next prev parent reply other threads:[~2019-04-23 18:38 UTC|newest] Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-04-22 22:43 Alex Williamson 2019-04-23 0:05 ` Alex G 2019-04-23 0:33 ` Alex Williamson 2019-04-23 14:33 ` Alex G 2019-04-23 15:34 ` Alex Williamson 2019-04-23 15:49 ` Lukas Wunner 2019-04-23 16:03 ` Alex G 2019-04-23 16:22 ` Alex Williamson 2019-04-23 16:27 ` Alex G 2019-04-23 16:37 ` Alex Williamson 2019-04-23 17:10 ` Bjorn Helgaas 2019-04-23 17:53 ` Alex G 2019-04-23 18:38 ` Alex Williamson [this message] 2019-04-23 17:59 ` Alex G 2019-05-01 20:30 ` Bjorn Helgaas
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