From: Simon Horman <horms@kernel.org>
To: Christoph Paasch <cpaasch@apple.com>
Cc: netdev <netdev@vger.kernel.org>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>, Jakub Kicinski <kuba@kernel.org>,
David Miller <davem@davemloft.net>,
Roopa Prabhu <roopa@nvidia.com>,
Craig Taylor <cmtaylor@apple.com>
Subject: Re: [PATCH netnext] mpls: Reduce skb re-allocations due to skb_cow()
Date: Mon, 19 Aug 2024 10:34:41 +0100 [thread overview]
Message-ID: <20240819093441.GC11472@kernel.org> (raw)
In-Reply-To: <967C2745-1EDB-464E-9C80-46345CA91650@apple.com>
On Fri, Aug 16, 2024 at 03:20:03PM -0700, Christoph Paasch wrote:
> Hello!
>
> > On Aug 16, 2024, at 4:18 AM, Simon Horman <horms@kernel.org> wrote:
> >
> > On Thu, Aug 15, 2024 at 09:12:01AM -0700, Christoph Paasch wrote:
> >> mpls_xmit() needs to prepend the MPLS-labels to the packet. That implies
> >> one needs to make sure there is enough space for it in the headers.
> >>
> >> Calling skb_cow() implies however that one wants to change even the
> >> playload part of the packet (which is not true for MPLS). Thus, call
> >> skb_cow_head() instead, which is what other tunnelling protocols do.
> >>
> >> Running a server with this comm it entirely removed the calls to
> >> pskb_expand_head() from the callstack in mpls_xmit() thus having
> >> significant CPU-reduction, especially at peak times.
> >
> > Hi Christoph and Craig,
> >
> > Including some performance data here would be nice.
>
> Getting exact production performance data is going to be a major challenge. Not a technical challenge, but rather logistically, ...
Understood :)
next prev parent reply other threads:[~2024-08-19 9:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-15 16:12 [PATCH netnext] mpls: Reduce skb re-allocations due to skb_cow() Christoph Paasch
2024-08-16 11:18 ` Simon Horman
2024-08-16 22:20 ` Christoph Paasch
2024-08-19 9:34 ` Simon Horman [this message]
2024-08-17 1:00 ` patchwork-bot+netdevbpf
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