From: Jesper Dangaard Brouer <brouer@redhat•com>
To: Saeed Mahameed <saeedm@mellanox•com>
Cc: "mst@redhat•com" <mst@redhat•com>, "toke@toke•dk" <toke@toke•dk>,
"dsahern@gmail•com" <dsahern@gmail•com>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>,
"pstaszewski@itcare•pl" <pstaszewski@itcare•pl>,
"davem@davemloft•net" <davem@davemloft•net>,
"jasowang@redhat•com" <jasowang@redhat•com>,
brouer@redhat•com
Subject: Re: consistency for statistics with XDP mode
Date: Sat, 1 Dec 2018 12:22:52 +0100 [thread overview]
Message-ID: <20181201122252.54833841@redhat.com> (raw)
In-Reply-To: <004d9dfec69c910f5677e5a2f7cf6e15b0dddee2.camel@mellanox.com>
On Fri, 30 Nov 2018 23:54:10 +0000
Saeed Mahameed <saeedm@mellanox•com> wrote:
> On Fri, 2018-11-30 at 15:30 -0500, Michael S. Tsirkin wrote:
> > On Fri, Nov 30, 2018 at 08:10:58PM +0000, Saeed Mahameed wrote:
> > > On Thu, 2018-11-22 at 18:00 +0100, Toke Høiland-Jørgensen wrote:
> > > > David Ahern <dsahern@gmail•com> writes:
> > > >
> > > > > On 11/22/18 1:26 AM, Toke Høiland-Jørgensen wrote:
> > > > > > Saeed Mahameed <saeedm@mellanox•com> writes:
> > > > > >
> > > > > > > > > I'd say it sounds reasonable to include XDP in the
> > > > > > > > > normal
> > > > > > > > > traffic
> > > > > > > > > counters, but having the detailed XDP-specific counters
> > > > > > > > > is
> > > > > > > > > quite
> > > > > > > > > useful
> > > > > > > > > as well... So can't we do both (for all drivers)?
> > > > > > > > >
> > > > > > >
> > > > > > > What are you thinking ?
> > > > > > > reporting XDP_DROP in interface dropped counter ?
> > > > > > > and XDP_TX/REDIRECT in the TX counter ?
> > > > > > > XDP_ABORTED in the err/drop counter ?
> > > > > > >
> > > > > > > how about having a special XDP command in the .ndo_bpf that
> > > > > > > would query
> > > > > > > the standardized XDP stats ?
> > > > > > the XDP-specific stats are useful to have separately as well
> > > > > > :)
> > > > > >
> > > > >
> > > > > I would like to see basic packets, bytes, and dropped counters
> > > > > tracked
> > > > > for Rx and Tx via the standard netdev counters for all
> > > > > devices.
> > >
> > > The problem of reporting XDP_DROP in the netedev drop counter is
> > > that
> > > they don't fit this counter description : "no space in linux
> > > buffers"
> > > and it will be hard for the user to determine whether these drops
> > > are
> > > coming from XDP or because no buffer is available, which will make
> > > it
> > > impossible to estimate packet rate performance without looking at
> > > ethtool stats.
> > > And reporting XDP_DROP in the netdev rx packets counter is somehow
> > > misleading.. since those packets never made it out of this
> > > driver..
> > >
> > >
> > > And reporting XDP_DROP in the netdev rx packets counter is somehow
> > > misleading.. since those packets never made it out of this driver..
> >
> > I think I agree. XDP needs minimal overhead - if user wants to do
> > counters then user can via maps. And in a sense XDP dropping packet
> > is much like e.g. TCP dropping packet - it is not counted
> > against the driver since it's not driver's fault.
>
> So we should count all XDP RX packets as successful rx packets i.e
> netdev->stats.rx_packets++; regardless of the XDP program decision ?
Yes.
> this implies that XDP_TX packets will be counted twice once in
> netdev->stats.rx_packets and once in netdev->stats.tx_packets
Yes, because the packet was RX'ed on the interface, and then TX'ed on
the interface. Users expect to see these packets (ac)counted.
> I think this is the only valid option if we are going to use standard
> netdev stats for XDP use cases.
IMHO XDP_DROP should not be accounted as netdev stats drops, this is a
user installed program like tc/iptables, that can also choose to drop
packets.
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
next prev parent reply other threads:[~2018-12-01 22:35 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-21 21:06 consistency for statistics with XDP mode David Ahern
2018-11-21 21:14 ` Toke Høiland-Jørgensen
2018-11-21 21:29 ` Paweł Staszewski
2018-11-22 0:21 ` Saeed Mahameed
2018-11-22 8:26 ` Toke Høiland-Jørgensen
2018-11-22 16:51 ` David Ahern
2018-11-22 17:00 ` Toke Høiland-Jørgensen
2018-11-30 20:10 ` Saeed Mahameed
2018-11-30 20:30 ` Michael S. Tsirkin
2018-11-30 20:35 ` David Ahern
2018-12-01 4:41 ` Jakub Kicinski
2018-12-01 11:14 ` Jesper Dangaard Brouer
2018-12-03 15:56 ` David Ahern
2018-12-03 19:32 ` David Miller
2018-11-30 23:54 ` Saeed Mahameed
2018-12-01 11:22 ` Jesper Dangaard Brouer [this message]
2018-12-03 15:45 ` David Ahern
2018-12-03 19:30 ` David Miller
2018-12-03 19:41 ` Arnaldo Carvalho de Melo
2018-12-03 20:00 ` Toke Høiland-Jørgensen
2018-12-04 0:00 ` David Miller
2018-12-04 0:15 ` David Ahern
2018-12-04 0:36 ` David Miller
2018-12-04 7:03 ` Toke Høiland-Jørgensen
2018-12-04 7:24 ` Jakub Kicinski
2018-12-04 9:29 ` Jesper Dangaard Brouer
2018-12-04 17:56 ` Jakub Kicinski
2018-12-04 18:06 ` Michael S. Tsirkin
2018-11-24 7:07 ` David Miller
2018-11-22 0:53 ` Toshiaki Makita
2018-11-22 16:43 ` David Ahern
2018-11-26 1:37 ` Toshiaki Makita
2018-11-27 7:04 ` Toshiaki Makita
2018-11-28 4:03 ` Jason Wang
2018-11-28 5:09 ` Toshiaki Makita
2018-11-26 22:15 ` Jakub Kicinski
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