[PATCH] ethdev: document that stats reset APIs are not thread-safe

[Morten Brørup]

> From: Stephen Hemminger [mailto:stephen at networkplumber.org]
> Sent: Friday, 26 April 2024 17.14
> 
> On Fri, 26 Apr 2024 14:20:01 +0200
> Morten Brørup <mb at smartsharesystems.com> wrote:
> 
> > > From: Ferruh Yigit [mailto:ferruh.yigit at amd.com]
> > > Sent: Thursday, 25 April 2024 18.53
> > >
> > > Making 'rte_eth_stats_reset()' and 'rte_eth_xstats_reset()' APIs thread
> > > safe has performance impact on datapath.
> > >
> > > Instead document APIs as not thread safe and add condition for reliable
> > > stats reset functionality, forwarding should be stopped.
> >
> > I'm not sure stopping forwarding suffices.
> > NIC hardware counters will keep progressing unless RX and TX is stopped at
> NIC level.
> >
> > I don't have any suggestions for a better wording, though. :-(
> >
> > Anyway, better with the patch than without...
> > Acked-by: Morten Brørup <mb at smartsharesystems.com>
> >
> 
> The safest option would be:
> 	rte_eth_dev_stop
> 	rte_eth_stats_reset
> 	rte_eth_dev_start

Yes, but this will cause packet loss.
Network admins should be able to clear the counters without causing packet loss.