From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8DA9DCA9EB5 for ; Mon, 21 Oct 2019 09:50:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5F2E42070B for ; Mon, 21 Oct 2019 09:50:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="ECAw3huD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727644AbfJUJuJ (ORCPT ); Mon, 21 Oct 2019 05:50:09 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:45774 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727110AbfJUJuJ (ORCPT ); Mon, 21 Oct 2019 05:50:09 -0400 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x9L9nLSo194538; Mon, 21 Oct 2019 09:50:00 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2019-08-05; bh=rsUd3DzB9xT/W7zLo5aVLsPVRAKbb0M7zYLFyN9ZA3M=; b=ECAw3huDS90YFA1/3eV5qfsj1fxNoFlQ8JRTDPMnWTSYGjnfyUoaGAAOcOS6po11+FJM L0lBdVda3nY4SaR1e66aEuXMwA49Mu4b2Sry26Gs9KNCQ5k6itX3nPSAjyIriJxSIEwo lgEWQrCW6L8UiyIZ8GUemq4Fwy3CXUmPy2FL5yfYNfbutK9CRwB13RCNzdy75d4hjPcC 5Sa/JxzlHSRxRUhDcsqGKedC+T/R/pzP+erJicOZ5MHZ+IJN/l5BzGbGZrvaZUUkJRF7 clTaHe3en7rH/8pQ+GXoGoJgdC1DXvgDV6LBVtJarJds54sDM2Hzim8rBFKlrbF9pq5+ 4g== Received: from userp3030.oracle.com (userp3030.oracle.com [156.151.31.80]) by aserp2120.oracle.com with ESMTP id 2vqtepehj2-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 21 Oct 2019 09:50:00 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x9L9nBWw177986; Mon, 21 Oct 2019 09:49:59 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userp3030.oracle.com with ESMTP id 2vrbxsuwwc-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 21 Oct 2019 09:49:59 +0000 Received: from abhmp0012.oracle.com (abhmp0012.oracle.com [141.146.116.18]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x9L9nwlf005259; Mon, 21 Oct 2019 09:49:58 GMT Received: from [10.182.71.192] (/10.182.71.192) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 21 Oct 2019 02:49:57 -0700 Subject: Re: [PATCH] net: forcedeth: add xmit_more support To: Jakub Kicinski Cc: rain.1986.08.12@gmail.com, davem@davemloft.net, netdev@vger.kernel.org References: <1571392885-32706-1-git-send-email-yanjun.zhu@oracle.com> <20191018154844.34a27c64@cakuba.netronome.com> From: Zhu Yanjun Organization: Oracle Corporation Message-ID: <84839e5f-4543-bbd9-37db-e1777a84992c@oracle.com> Date: Mon, 21 Oct 2019 17:56:06 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20191018154844.34a27c64@cakuba.netronome.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-GB X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9416 signatures=668684 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=892 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1910210094 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9416 signatures=668684 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=975 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1910210094 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2019/10/19 6:48, Jakub Kicinski wrote: > On Fri, 18 Oct 2019 06:01:25 -0400, Zhu Yanjun wrote: >> This change adds support for xmit_more based on the igb commit 6f19e12f6230 >> ("igb: flush when in xmit_more mode and under descriptor pressure") and >> commit 6b16f9ee89b8 ("net: move skb->xmit_more hint to softnet data") that >> were made to igb to support this feature. The function netif_xmit_stopped >> is called to check if transmit queue on device is currently unable to send >> to determine if we must write the tail because we can add no further >> buffers. >> When normal packets and/or xmit_more packets fill up tx_desc, it is >> necessary to trigger NIC tx reg. > Looks broken. You gotta make sure you check the kick on _every_ return > path. There are 4 return statements in each function, you only touched > 2. In nv_start_xmit, 2240         if (unlikely(empty_slots <= entries)) { 2241                 netif_stop_queue(dev); 2242                 np->tx_stop = 1; 2243                 spin_unlock_irqrestore(&np->lock, flags); 2244 2245                 /* When normal packets and/or xmit_more packets fill up 2246                  * tx_desc, it is necessary to trigger NIC tx reg. 2247                  */ 2248                 ret = NETDEV_TX_BUSY; 2249                 goto TXKICK; 2250         } The above indicates tx_desc is full, it is necessary to trigger NIC HW xmit. 2261                 if (unlikely(dma_mapping_error(&np->pci_dev->dev, 2262 np->put_tx_ctx->dma))) { 2263                         /* on DMA mapping error - drop the packet */ 2264                         dev_kfree_skb_any(skb); 2265 u64_stats_update_begin(&np->swstats_tx_syncp); 2266                         nv_txrx_stats_inc(stat_tx_dropped); 2267 u64_stats_update_end(&np->swstats_tx_syncp); 2268                         return NETDEV_TX_OK; 2269                 } and 2300                         if (unlikely(dma_mapping_error(&np->pci_dev->dev, 2301 np->put_tx_ctx->dma))) { 2302 2303                                 /* Unwind the mapped fragments */ 2304                                 do { 2305                                         nv_unmap_txskb(np, start_tx_ctx); 2306                                         if (unlikely(tmp_tx_ctx++ == np->last_tx_ctx)) 2307                                                 tmp_tx_ctx = np->tx_skb; 2308                                 } while (tmp_tx_ctx != np->put_tx_ctx); 2309                                 dev_kfree_skb_any(skb); 2310                                 np->put_tx_ctx = start_tx_ctx; 2311 u64_stats_update_begin(&np->swstats_tx_syncp); 2312 nv_txrx_stats_inc(stat_tx_dropped); 2313 u64_stats_update_end(&np->swstats_tx_syncp); 2314                                 return NETDEV_TX_OK; 2315                         } The above are dma_mapping_error. It seems that triggering NIC HW xmit is not needed. So when "tx_desc full" error, HW NIC xmit is triggerred. When dma_mapping_error, NIC HW xmit is not triggerred. That is why only 2 "return" are touched. > > Also the labels should be lower case. This patch passes checkpatch.pl. It seems that "not lower case" is not a problem? If you think it is a problem, please show me where it is defined. Zhu Yanjun >