netdev - Re: [PATCH net-next] selftests: drv-net: assume stats refresh is 0 if no ethtool -c support

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Message-ID: <c102ecbd-e1a6-4b89-bef5-110744345478@lunn.ch>
Date: Fri, 20 Dec 2024 16:03:39 +0100
From: Andrew Lunn <andrew@...n.ch>
To: Jakub Kicinski <kuba@...nel.org>
Cc: davem@...emloft.net, netdev@...r.kernel.org, edumazet@...gle.com,
	pabeni@...hat.com, shuah@...nel.org, willemb@...gle.com,
	petrm@...dia.com, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH net-next] selftests: drv-net: assume stats refresh is 0
 if no ethtool -c support

On Fri, Dec 20, 2024 at 06:22:14AM -0800, Jakub Kicinski wrote:
> On Fri, 20 Dec 2024 10:09:06 +0100 Andrew Lunn wrote:
> > > @@ -234,7 +234,12 @@ from .remote import Remote
> > >          Good drivers will tell us via ethtool what their sync period is.
> > >          """
> > >          if self._stats_settle_time is None:
> > > -            data = ethtool("-c " + self.ifname, json=True)[0]
> > > +            data = {}
> > > +            try:
> > > +                data = ethtool("-c " + self.ifname, json=True)[0]
> > > +            except CmdExitFailure as e:
> > > +                if "Operation not supported" not in e.cmd.stderr:
> > > +                    raise  
> > 
> > How important is this time to the test itself? 
> 
> Just to be clear (because unfortunately git doesn't do a good job of
> calling out Python method names in the diff :() this is part of a
> method called wait_hw_stats_settle() within the test env class. 
> It's used by various tests which use/check device stats.
> 
> > If it is not available,
> > can the test just default to 50ms and keep going? I would of thought
> > we find more issues by running the test too slowly, than not running
> > it at all, unless having the wrong timer makes it more flaky.
> 
> We already use zero for majority of driver which don't report stat
> refresh:
> 
>                  data.get('stats-block-usecs', 0) / 1000 / 1000
>                                               ^^^
> this patch just does the same thing not only if the driver doesn't
> report 'stats-block-usecs' but also if it doesn't support -c at all.

[Looks at it again] So the raise is if ethtool give an error other
than EOPNOTUPP, so a real error. O.K. Then i makes sense.

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew