From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751952AbdGFJQi (ORCPT ); Thu, 6 Jul 2017 05:16:38 -0400 Received: from mail-wr0-f193.google.com ([209.85.128.193]:33365 "EHLO mail-wr0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750778AbdGFJQg (ORCPT ); Thu, 6 Jul 2017 05:16:36 -0400 Message-ID: <1499332587.16045.13.camel@edumazet-glaptop3.roam.corp.google.com> Subject: Re: [PATCH net-next] skbuff: optimize the pull_pages code in __pskb_pull_tail() From: Eric Dumazet To: Lin Zhang Cc: davem@davemloft.net, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Date: Thu, 06 Jul 2017 02:16:27 -0700 In-Reply-To: <1499331694-34678-1-git-send-email-xiaolou4617@gmail.com> References: <1499331694-34678-1-git-send-email-xiaolou4617@gmail.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4-0ubuntu2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2017-07-06 at 17:01 +0800, Lin Zhang wrote: > In the pull_pages code block, if the first frags size > eat, > we can end the loop in advance to avoid extra copy. > > Signed-off-by: Lin Zhang > --- > net/core/skbuff.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > index f990eb8..c00a1df 100644 > --- a/net/core/skbuff.c > +++ b/net/core/skbuff.c > @@ -1720,6 +1720,10 @@ void *__pskb_pull_tail(struct sk_buff *skb, int delta) > skb_shinfo(skb)->frags[k].page_offset += eat; > skb_frag_size_sub(&skb_shinfo(skb)->frags[k], eat); > eat = 0; > + if (!i) { > + k = skb_shinfo(skb)->nr_frags; > + break; > + } > } > k++; > } 1) net-next is closed during merge window. 2) This change is completely buggy. How have you tested it exactly ???