From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934252AbaHZJFL (ORCPT ); Tue, 26 Aug 2014 05:05:11 -0400 Received: from mout.kundenserver.de ([212.227.17.10]:58272 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932634AbaHZJFI (ORCPT ); Tue, 26 Aug 2014 05:05:08 -0400 From: Arnd Bergmann To: linux-arm-kernel@lists.infradead.org Cc: Jonas Jensen , netdev@vger.kernel.org, f.fainelli@gmail.com, eric.dumazet@gmail.com, linux-kernel@vger.kernel.org, mirqus@gmail.com, davem@davemloft.net Subject: Re: [PATCH v6 2/4] net: moxa: replace build_skb() with netdev_alloc_skb_ip_align() / memcpy() Date: Tue, 26 Aug 2014 11:04:30 +0200 Message-ID: <4449672.aCJ5J5rv4r@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.16.0-10-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: <1408976542-15624-1-git-send-email-jonas.jensen@gmail.com> References: <1408544342-32058-1-git-send-email-jonas.jensen@gmail.com> <1408976542-15624-1-git-send-email-jonas.jensen@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V02:K0:o95fdKvYf3bTnE3BFwbdc7JIpPIAnOuOXjig+dTYr2z NAtXTLxj6OheAWO4hZ21G057YKNPBBM3vFVqXnG739lgmBadm+ 2D8bLlOaR+93WvUS3aMc0/8meTzTNvC2qC6rHTYz94OG1d3+31 1c4sFPz/O29qiaqSfcih5HHHt+T6mdoJe+1lCTwUKbsxeZzT+t lquQqP6oeMDPGKkuE69ofBit64wEVdR0ZRRNvNMf75ysEtSUaj YMK6mm12yI0MSxdCpp9pFW3l/p/7K7NLvfjW7MMvsTw7aoLb6z naV8w0MKIDklv8Dt+j3IkZRw8mmR6z8UL4IKceP+HcNjFzF5u2 +7JUsEHoiHSqk8VuCE5A= X-UI-Out-Filterresults: notjunk:1; Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday 25 August 2014 16:22:22 Jonas Jensen wrote: > @@ -226,13 +226,15 @@ static int moxart_rx_poll(struct napi_struct *napi, int budget) > if (len > RX_BUF_SIZE) > len = RX_BUF_SIZE; > > - skb = build_skb(priv->rx_buf[rx_head], priv->rx_buf_size); > + skb = netdev_alloc_skb_ip_align(ndev, len); > + > if (unlikely(!skb)) { > - net_dbg_ratelimited("build_skb failed\n"); > + net_dbg_ratelimited("netdev_alloc_skb_ip_align failed\n"); > priv->stats.rx_dropped++; > priv->stats.rx_errors++; > } > > + memcpy(skb->data, priv->rx_buf[rx_head], len); > skb_put(skb, len); > skb->protocol = eth_type_trans(skb, ndev); > napi_gro_receive(&priv->napi, skb); While this seems correct, I wonder why you don't do the normal approach of dequeuing the skb from the chain and adding a newly allocated skb to it to save the memcpy. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Tue, 26 Aug 2014 11:04:30 +0200 Subject: [PATCH v6 2/4] net: moxa: replace build_skb() with netdev_alloc_skb_ip_align() / memcpy() In-Reply-To: <1408976542-15624-1-git-send-email-jonas.jensen@gmail.com> References: <1408544342-32058-1-git-send-email-jonas.jensen@gmail.com> <1408976542-15624-1-git-send-email-jonas.jensen@gmail.com> Message-ID: <4449672.aCJ5J5rv4r@wuerfel> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Monday 25 August 2014 16:22:22 Jonas Jensen wrote: > @@ -226,13 +226,15 @@ static int moxart_rx_poll(struct napi_struct *napi, int budget) > if (len > RX_BUF_SIZE) > len = RX_BUF_SIZE; > > - skb = build_skb(priv->rx_buf[rx_head], priv->rx_buf_size); > + skb = netdev_alloc_skb_ip_align(ndev, len); > + > if (unlikely(!skb)) { > - net_dbg_ratelimited("build_skb failed\n"); > + net_dbg_ratelimited("netdev_alloc_skb_ip_align failed\n"); > priv->stats.rx_dropped++; > priv->stats.rx_errors++; > } > > + memcpy(skb->data, priv->rx_buf[rx_head], len); > skb_put(skb, len); > skb->protocol = eth_type_trans(skb, ndev); > napi_gro_receive(&priv->napi, skb); While this seems correct, I wonder why you don't do the normal approach of dequeuing the skb from the chain and adding a newly allocated skb to it to save the memcpy. Arnd