Re: [dpdk-dev] [PATCH 1/2] ethdev: fix log level of Tx and Rx dummy functions

[Thomas Monjalon <thomas@monjalon.net>]

24/10/2021 13:48, Ananyev, Konstantin:
> 
> > > > > When stopping a port, the data path Tx and Rx burst functions
> > > should
> > > > > be stopped firstly conventionally. Then the dummy functions are
> > > used
> > > > > to replace the callback functions provided by the PMD.
> > > > >
> > > > > When the application stops a port without or before stopping the
> > > > > data path handling.
> > >
> > > If the application really does that, then it is a severe bug in the
> > > application, then needs to be fixed ASAP.
> > 
> > I agree, this should be some improper / wrong behavior in the application.
> > 
> > >
> > > > The dummy functions may be invoked heavily and a lot
> > > > > of logs in these dummy functions will result in a flood.
> > > >
> > > > Why does it happen? We should not use a stopped port.
> > > > Is it a problem of core synchronization?
> > > >
> > > > > Debug level log should be enough instead of the error level.
> > > >
> > > >
> > >
> > > Dummy function is supposed to be set only when device is not able to
> > > do RX/TX properly (not attached, or attached but not configured, or
> > > attached and configured, but not started).
> > > Obviously if app calls rx/tx_burst for such port it is a major issue,
> > > that should be flagged immediately.
> > > So I believe having ERR level here makes a perfect sense here.
> > 
> > I do not insist on this. Some notification to the application may be needed. While to my understanding, the log flood should be prevented,
> > or the logs may slow down the application, the IO, and would also have impact on other logs and some information may get lost (but that is
> > the users' decision).
> > Since the rx/tx burst are usually in the data path and invoked heavily, if the log is needed, how about print it only once? WDYT?
> > 
> 
> Correctly behaving app should never call these stub functions and should never see these messages.
> If your app ended up inside this function, then there something really wrong is going on,
> that can cause app crash, silent memory corruption, NIC HW hang, or many other nasty things.
> The aim of this stubs mechanism:
> 1) minimize (but not completely avoid) risk of such damage to happen in case of
>     programming error within user app.
> 2) flag to the user that something very wrong is going on within his app.
> In such situation, possible slowdown of misbehaving program is out of my concern.  

There is a concern about getting efficient log report,
especially when looking at CI issues.