linux-kernel - Re: [External] Re: [PATCH net] veth: fix ethtool statistical errors

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Message-ID: <ZVssMWXZYxM0eKiY@lore-desk>
Date:   Mon, 20 Nov 2023 10:51:45 +0100
From:   Lorenzo Bianconi <lorenzo@...nel.org>
To:     黄杰 <huangjie.albert@...edance.com>
Cc:     Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Toshiaki Makita <toshiaki.makita1@...il.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [External] Re: [PATCH net] veth: fix ethtool statistical errors

> Lorenzo Bianconi <lorenzo@...nel.org> 于2023年11月17日周五 17:26写道：
> >
> > > if peer->real_num_rx_queues > 1, the ethtool -s command for
> > > veth network device will display some error statistical values.
> > > The value of tx_idx is reset with each iteration, so even if
> > > peer->real_num_rx_queues is greater than 1, the value of tx_idx
> > > will remain constant. This results in incorrect statistical values.
> > > To fix this issue, assign the value of pp_idx to tx_idx.
> > >
> > > Fixes: 5fe6e56776ba ("veth: rely on peer veth_rq for ndo_xdp_xmit accounting")
> > > Signed-off-by: Albert Huang <huangjie.albert@...edance.com>
> > > ---
> > >  drivers/net/veth.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/net/veth.c b/drivers/net/veth.c
> > > index 0deefd1573cf..3a8e3fc5eeb5 100644
> > > --- a/drivers/net/veth.c
> > > +++ b/drivers/net/veth.c
> > > @@ -225,7 +225,7 @@ static void veth_get_ethtool_stats(struct net_device *dev,
> > >       for (i = 0; i < peer->real_num_rx_queues; i++) {
> > >               const struct veth_rq_stats *rq_stats = &rcv_priv->rq[i].stats;
> > >               const void *base = (void *)&rq_stats->vs;
> > > -             unsigned int start, tx_idx = idx;
> > > +             unsigned int start, tx_idx = pp_idx;
> > >               size_t offset;
> > >
> > >               tx_idx += (i % dev->real_num_tx_queues) * VETH_TQ_STATS_LEN;
> > > --
> > > 2.20.1
> > >
> >
> > Hi Albert,
> >
> > Can you please provide more details about the issue you are facing?
> > In particular, what is the number of configured tx and rx queues for both
> > peers?
> 
> Hi, Lorenzo
> I found this because I wanted to add more echo information in ethttool（for veth,
> but I found that the information was incorrect. That's why I paid
> attention here.

ack. Could you please share the veth pair tx/rx queue configuration?

Rergards,
Lorenzo

> 
> > tx_idx is the index of the current (local) tx queue and it must restart from
> > idx in each iteration otherwise we will have an issue when
> > peer->real_num_rx_queues is greater than dev->real_num_tx_queues.
> >
> OK. I don't know if this is a known issue.
> 
> BR
> Albert
> 
> 
> > Regards,
> > Lorenzo

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