From mboxrd@z Thu Jan 1 00:00:00 1970 From: Claudiu Manoil Subject: Re: [PATCH][net-next] gianfar: Fix reported sent bytes to BQL for Tx timestamping Date: Mon, 29 Apr 2013 18:52:34 +0300 Message-ID: <517E9742.1010002@freescale.com> References: <1367240268-32609-1-git-send-email-claudiu.manoil@freescale.com> <1367243593.8964.306.camel@edumazet-glaptop> <517E8354.1010503@freescale.com> <1367249009.8964.312.camel@edumazet-glaptop> <1367249315.8964.314.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit Cc: , Paul Gortmaker , "David S. Miller" To: Eric Dumazet Return-path: Received: from [65.55.88.14] ([65.55.88.14]:23220 "EHLO tx2outboundpool.messaging.microsoft.com" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1757091Ab3D2Px5 (ORCPT ); Mon, 29 Apr 2013 11:53:57 -0400 In-Reply-To: <1367249315.8964.314.camel@edumazet-glaptop> Sender: netdev-owner@vger.kernel.org List-ID: On 4/29/2013 6:28 PM, Eric Dumazet wrote: > On Mon, 2013-04-29 at 08:23 -0700, Eric Dumazet wrote: >> On Mon, 2013-04-29 at 17:27 +0300, Claudiu Manoil wrote: >>> Hi, >>> >>> Unfortunately fixing this the other way around would imply changes >>> in both xmit and clean_tx, and additional overhead in clean_tx. >>> On xmit skb->len gets incremented with FCB_LEN and/or TXPAL_LEN, >>> on a case by case basis. This would imply to add extra checks on >>> clean_tx to identify whether only FCB_LEN has been added, or >>> FCB+TXPAL or neither, all these just to report the bytes on wire >>> for BQL. >>> Does BQL really need to measure the bytes-on-wire or the bytes consumed >>> for buffering? >> >> Yes. >> >> What about : >> >> diff --git a/drivers/net/ethernet/freescale/gianfar.c b/drivers/net/ethernet/freescale/gianfar.c >> index 2375a01..bb727e1 100644 >> --- a/drivers/net/ethernet/freescale/gianfar.c >> +++ b/drivers/net/ethernet/freescale/gianfar.c >> @@ -2065,6 +2065,7 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev) >> u32 bufaddr; >> unsigned long flags; >> unsigned int nr_frags, nr_txbds, length, fcb_length = GMAC_FCB_LEN; >> + unsigned int len; >> >> /* TOE=1 frames larger than 2500 bytes may see excess delays >> * before start of transmission. >> @@ -2130,7 +2131,8 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev) >> } >> >> /* Update transmit stats */ >> - tx_queue->stats.tx_bytes += skb->len; >> + len = skb->len; Already tried this change in xmit, but it breaks the UDP/TCP cases (eg. ftp). Due to (skb->ip_summed == CHECKSUM_PARTIAL) condition FCB is added on xmit (skb->len increased with FCB_LEN only), and Tx completion does not make this check. > Idea is to use this value in TX completion. > > If at tx completion skb->len might be different, then store the true > skb->len in skb->cb[] > Interesting but non-trivial, I think. Is this allowed? I mean, doesn't the net stack overwrite this field? Thanks, Claudiu