From: Eric Dumazet <eric.dumazet@gmail.com>
To: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: John Fastabend <john.fastabend@gmail.com>,
Alexander Duyck <alexander.duyck@gmail.com>,
Netdev <netdev@vger.kernel.org>,
Tom Herbert <tom@herbertland.com>,
Alexei Starovoitov <ast@kernel.org>,
John Fastabend <john.r.fastabend@intel.com>,
Daniel Borkmann <daniel@iogearbox.net>,
David Miller <davem@davemloft.net>
Subject: Re: Questions on XDP
Date: Sat, 18 Feb 2017 09:41:15 -0800 [thread overview]
Message-ID: <1487439675.1311.96.camel@edumazet-glaptop3.roam.corp.google.com> (raw)
In-Reply-To: <20170218173402.1af86005@redhat.com>
On Sat, 2017-02-18 at 17:34 +0100, Jesper Dangaard Brouer wrote:
> On Thu, 16 Feb 2017 14:36:41 -0800
> John Fastabend <john.fastabend@gmail.com> wrote:
>
> > On 17-02-16 12:41 PM, Alexander Duyck wrote:
> > > So I'm in the process of working on enabling XDP for the Intel NICs
> > > and I had a few questions so I just thought I would put them out here
> > > to try and get everything sorted before I paint myself into a corner.
> > >
> > > So my first question is why does the documentation mention 1 frame per
> > > page for XDP?
>
> Yes, XDP defines upfront a memory model where there is only one packet
> per page[1], please respect that!
>
> This is currently used/needed for fast-direct recycling of pages inside
> the driver for XDP_DROP and XDP_TX, _without_ performing any atomic
> refcnt operations on the page. E.g. see mlx4_en_rx_recycle().
XDP_DROP does not require having one page per frame.
(Look after my recent mlx4 patch series if you need to be convinced)
Only XDP_TX is.
This requirement makes XDP useless (very OOM likely) on arches with 64K
pages.
next prev parent reply other threads:[~2017-02-18 17:41 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-16 20:41 Questions on XDP Alexander Duyck
2017-02-16 22:36 ` John Fastabend
2017-02-18 16:34 ` Jesper Dangaard Brouer
2017-02-18 17:41 ` Eric Dumazet [this message]
2017-02-18 18:18 ` Alexander Duyck
2017-02-18 23:28 ` John Fastabend
2017-02-18 23:31 Alexei Starovoitov
2017-02-18 23:48 ` John Fastabend
2017-02-18 23:59 ` Eric Dumazet
2017-02-19 2:16 ` Alexander Duyck
2017-02-19 3:48 ` John Fastabend
2017-02-20 20:06 ` Jakub Kicinski
2017-02-22 5:02 ` John Fastabend
2017-02-21 3:18 ` Alexei Starovoitov
2017-02-21 3:39 ` John Fastabend
2017-02-21 4:00 ` Alexander Duyck
2017-02-21 7:55 ` Alexei Starovoitov
2017-02-21 17:44 ` Alexander Duyck
2017-02-22 17:08 ` John Fastabend
2017-02-22 21:59 ` Jesper Dangaard Brouer
2017-02-18 23:59 Alexei Starovoitov
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