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From: Thomas Monjalon <thomas@monjalon.net>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
Cc: Bing Zhao <bingz@nvidia.com>,
	"Yigit, Ferruh" <ferruh.yigit@intel.com>,
	"andrew.rybchenko@oktetlabs.ru" <andrew.rybchenko@oktetlabs.ru>,
	"dev@dpdk.org" <dev@dpdk.org>,
	david.marchand@redhat.com
Subject: Re: [dpdk-dev] [PATCH 1/2] ethdev: fix log level of Tx and Rx dummy functions
Date: Mon, 25 Oct 2021 11:43:08 +0200	[thread overview]
Message-ID: <2136748.9NGIIKDUHm@thomas> (raw)
In-Reply-To: <DM6PR11MB44913D01F3D28EE374059FF59A829@DM6PR11MB4491.namprd11.prod.outlook.com>

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.




  reply	other threads:[~2021-10-25  9:43 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-22 21:14 Bing Zhao
2021-10-22 21:14 ` [dpdk-dev] [PATCH 2/2] ethdev: fix the race condition for fp ops reset Bing Zhao
2021-10-23  8:34   ` Thomas Monjalon
2021-10-23 11:39     ` Ananyev, Konstantin
2021-11-10 14:34       ` Ferruh Yigit
2021-11-10 14:37         ` Ananyev, Konstantin
2021-11-10 14:57           ` Thomas Monjalon
2021-11-10 15:24             ` Bing Zhao
2021-10-23 16:13   ` [dpdk-dev] " Stephen Hemminger
2021-10-24  5:54     ` Bing Zhao
2021-10-23  8:32 ` [dpdk-dev] [PATCH 1/2] ethdev: fix log level of Tx and Rx dummy functions Thomas Monjalon
2021-10-23 11:46   ` Ananyev, Konstantin
2021-10-23 12:45     ` Bing Zhao
2021-10-24 11:48       ` Ananyev, Konstantin
2021-10-25  9:43         ` Thomas Monjalon [this message]
2021-10-25  9:51           ` David Marchand
2021-10-25 12:55             ` Ananyev, Konstantin
2021-10-25 13:27               ` Thomas Monjalon
2021-10-25 13:31                 ` David Marchand
2021-10-25 20:29                   ` Ananyev, Konstantin
2021-10-25 20:38                     ` Thomas Monjalon
2021-10-26 12:38                       ` Ananyev, Konstantin
2021-10-26 12:59                         ` Thomas Monjalon
2021-10-26  3:18                   ` Bing Zhao
2021-10-23 12:12   ` Bing Zhao

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