From: Eric Dumazet <edumazet@google.com>
To: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Miller <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Pravin B Shelar <pshelar@ovn.org>,
Florian Westphal <fw@strlen.de>,
martin.varghese@nokia.com, Davide Caratti <dcaratti@redhat.com>,
Steffen Klassert <steffen.klassert@secunet.com>,
Paolo Abeni <pabeni@redhat.com>,
shmulik@metanetworks.com, kyk.segfault@gmail.com,
netdev <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] net: Set trailer iff skb1 is the last one
Date: Thu, 27 Aug 2020 04:35:32 -0700 [thread overview]
Message-ID: <CANn89iK3CKrXPj5fNYys26zd8P67jz8GZEF2WjLD6Xw05SimcA@mail.gmail.com> (raw)
In-Reply-To: <20200827112922.48889-1-linmiaohe@huawei.com>
On Thu, Aug 27, 2020 at 4:31 AM Miaohe Lin <linmiaohe@huawei.com> wrote:
>
> Set trailer iff skb1 is the skbuff where the tailbits space begins.
>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
> net/core/skbuff.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 0b24aed04060..18ed56316e56 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -4488,8 +4488,9 @@ int skb_cow_data(struct sk_buff *skb, int tailbits, struct sk_buff **trailer)
> skb1 = skb2;
> }
> elt++;
> - *trailer = skb1;
> skb_p = &skb1->next;
> + if (!*skb_p)
> + *trailer = skb1;
>
Why is adding a conditional test going to help ?
cpu will have hard time predicting this one, I doubt this kind of
change is a win.
prev parent reply other threads:[~2020-08-27 11:49 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-27 11:29 [PATCH] net: Set trailer iff skb1 is the last one Miaohe Lin
2020-08-27 11:35 ` Eric Dumazet [this message]
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