From: Jakub Kicinski <kuba@kernel.org>
To: Luigi Rizzo <lrizzo@google.com>
Cc: netdev@vger.kernel.org, toke@redhat.com, davem@davemloft.net,
hawk@kernel.org, sameehj@amazon.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4] netdev attribute to control xdpgeneric skb linearization
Date: Fri, 28 Feb 2020 11:00:43 -0800 [thread overview]
Message-ID: <20200228110043.2771fddb@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> (raw)
In-Reply-To: <20200228105435.75298-1-lrizzo@google.com>
On Fri, 28 Feb 2020 02:54:35 -0800 Luigi Rizzo wrote:
> Add a netdevice flag to control skb linearization in generic xdp mode.
>
> The attribute can be modified through
> /sys/class/net/<DEVICE>/xdpgeneric_linearize
> The default is 1 (on)
>
> Motivation: xdp expects linear skbs with some minimum headroom, and
> generic xdp calls skb_linearize() if needed. The linearization is
> expensive, and may be unnecessary e.g. when the xdp program does
> not need access to the whole payload.
> This sysfs entry allows users to opt out of linearization on a
> per-device basis (linearization is still performed on cloned skbs).
>
> On a kernel instrumented to grab timestamps around the linearization
> code in netif_receive_generic_xdp, and heavy netperf traffic with 1500b
> mtu, I see the following times (nanoseconds/pkt)
>
> The receiver generally sees larger packets so the difference is more
> significant.
>
> ns/pkt RECEIVER SENDER
>
> p50 p90 p99 p50 p90 p99
>
> LINEARIZATION: 600ns 1090ns 4900ns 149ns 249ns 460ns
> NO LINEARIZATION: 40ns 59ns 90ns 40ns 50ns 100ns
>
> v1 --> v2 : added Documentation
> v2 --> v3 : adjusted for skb_cloned
> v3 --> v4 : renamed to xdpgeneric_linearize, documentation
>
> Signed-off-by: Luigi Rizzo <lrizzo@google.com>
Just load your program in cls_bpf. No extensions or knobs needed.
Making xdpgeneric-only extensions without touching native XDP makes
no sense to me. Is this part of some greater vision?
next prev parent reply other threads:[~2020-02-28 19:00 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-28 10:54 [PATCH v4] netdev attribute to control xdpgeneric skb linearization Luigi Rizzo
2020-02-28 11:20 ` Toke Høiland-Jørgensen
2020-02-28 12:12 ` Michal Kubecek
2020-02-28 12:29 ` Jesper Dangaard Brouer
2020-02-28 13:19 ` Luigi Rizzo
2020-02-28 12:30 ` Jesper Dangaard Brouer
2020-02-28 19:00 ` Jakub Kicinski [this message]
2020-02-28 23:53 ` Willem de Bruijn
2020-03-03 19:46 ` Daniel Borkmann
2020-03-03 20:50 ` Jakub Kicinski
2020-03-03 21:04 ` Daniel Borkmann
2020-03-03 21:10 ` Willem de Bruijn
2020-03-04 9:18 ` Jesper Dangaard Brouer
2020-03-04 10:06 ` Luigi Rizzo
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