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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 60E15C433B4 for ; Wed, 12 May 2021 02:47:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 401EA61207 for ; Wed, 12 May 2021 02:47:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230109AbhELCs6 (ORCPT ); Tue, 11 May 2021 22:48:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46646 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229934AbhELCs4 (ORCPT ); Tue, 11 May 2021 22:48:56 -0400 Received: from mail-lj1-x231.google.com (mail-lj1-x231.google.com [IPv6:2a00:1450:4864:20::231]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 01A11C061761; Tue, 11 May 2021 19:39:51 -0700 (PDT) Received: by mail-lj1-x231.google.com with SMTP id e11so14165068ljn.13; Tue, 11 May 2021 19:39:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=BZrN9CKOIbxr+u9v7iLlbrVLgfzLx8ReH7EGaaO9x1I=; b=lbLifQDNCpqVolfi042QXh5WuwbLtkYvVO4+OKYLT1ZYeN0GZPdt6v0ZC01Ycp/AbC yJCUY6OLXls/8Uo/drc0huwWw41jxoKhZdjhuuZWpNteeOaTFUIVMHloI2IED1SmrhdV y7jdjA8mhzAA0tplfiMoCbYSeGmGJ0Ys28mA/qD0nWsVX8fTVdVWbfQKwfmRdrlINyvp xJl5DhqcNUqolDr56E6xNuBMzjpqsmpIpAZbKbVqCsM5SqJQ9Yiq/C5HPbEWpxn+4Fjl X3cDGlA0f9Sj+HiLpKZf9pnh5XDHEEx48gDlUj7bwlbmzWRqChr++rsGHefWQ/Rmnkzj iKEg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=BZrN9CKOIbxr+u9v7iLlbrVLgfzLx8ReH7EGaaO9x1I=; b=kpRqdX8tDZCzUxcaL/ZWuaagOnE4yhAkOzj9DoCmcht0xOGQpBWJ3OU+25UGvfodex IFlAvi/7Z74C1g8DOqzPy3UvTnudlxKKSFa8uy1+csgyohJfMSTc1EOP/U913V/SSe2T zlr2ziIEqYzfe7h9C5492oz502kjcWdBblVnBKNUHCUDO5tKkvJxvGu9xQQQQ/b8Ocj6 QSsuGAaePjvFbMTMy1aXpoCjT2Z4b/Eiz8UnLxYiEy6e/wworuAPto8j+kPtjJ5JGNCm WyXRFgjbsl9K2jPSIjESLtZ3xpyEraCHiYWOx2d9joWOIsEs0vo0wvw6BRFzp1pHa+49 YAGg== X-Gm-Message-State: AOAM531z3vnP5a5AUnQt3bT/lNY5369A/3WBk1Vxv04UgDGzmjwLskXX jUXscNn3fYFEcRzcAZxPjJLAD3u7U7bmK4jxdI4= X-Google-Smtp-Source: ABdhPJwUNWoD0sHexnPdDFMVCMFGnuaVCaQuZqImmT6XeZa5ItR8WaL/uitw2bleALjA3lJb1ACEe7B+DMbmJxgwQNg= X-Received: by 2002:a2e:a606:: with SMTP id v6mr27851429ljp.289.1620787189542; Tue, 11 May 2021 19:39:49 -0700 (PDT) MIME-Version: 1.0 References: <20210511190518.8901-1-gatis@mikrotik.com> <20210511190518.8901-3-gatis@mikrotik.com> In-Reply-To: <20210511190518.8901-3-gatis@mikrotik.com> From: Chris Snook Date: Tue, 11 May 2021 19:39:38 -0700 Message-ID: Subject: Re: [PATCH net-next 2/4] atl1c: improve performance by avoiding unnecessary pcie writes on xmit To: Gatis Peisenieks Cc: "David S. Miller" , Jakub Kicinski , Heiner Kallweit , jesse.brandeburg@intel.com, dchickles@marvell.com, tully@mikrotik.com, Eric Dumazet , netdev , LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Increases in latency tend to hurt more on single-queue devices. Has this been tested on the original gigabit atl1c? - Chris On Tue, May 11, 2021 at 12:05 PM Gatis Peisenieks wrote: > > The kernel has xmit_more facility that hints the networking driver xmit > path about whether more packets are coming soon. This information can be > used to avoid unnecessary expensive PCIe transaction per tx packet at a > slight increase in latency. > > Max TX pps on Mikrotik 10/25G NIC in a Threadripper 3960X system > improved from 1150Kpps to 1700Kpps. > > Signed-off-by: Gatis Peisenieks > --- > drivers/net/ethernet/atheros/atl1c/atl1c_main.c | 13 +++++++++---- > 1 file changed, 9 insertions(+), 4 deletions(-) > > diff --git a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c > index 28c30d5288e4..2a8ab51b0ed9 100644 > --- a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c > +++ b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c > @@ -2211,8 +2211,8 @@ static int atl1c_tx_map(struct atl1c_adapter *adapter, > return -1; > } > > -static void atl1c_tx_queue(struct atl1c_adapter *adapter, struct sk_buff *skb, > - struct atl1c_tpd_desc *tpd, enum atl1c_trans_queue type) > +static void atl1c_tx_queue(struct atl1c_adapter *adapter, > + enum atl1c_trans_queue type) > { > struct atl1c_tpd_ring *tpd_ring = &adapter->tpd_ring[type]; > u16 reg; > @@ -2238,6 +2238,7 @@ static netdev_tx_t atl1c_xmit_frame(struct sk_buff *skb, > > if (atl1c_tpd_avail(adapter, type) < tpd_req) { > /* no enough descriptor, just stop queue */ > + atl1c_tx_queue(adapter, type); > netif_stop_queue(netdev); > return NETDEV_TX_BUSY; > } > @@ -2246,6 +2247,7 @@ static netdev_tx_t atl1c_xmit_frame(struct sk_buff *skb, > > /* do TSO and check sum */ > if (atl1c_tso_csum(adapter, skb, &tpd, type) != 0) { > + atl1c_tx_queue(adapter, type); > dev_kfree_skb_any(skb); > return NETDEV_TX_OK; > } > @@ -2270,8 +2272,11 @@ static netdev_tx_t atl1c_xmit_frame(struct sk_buff *skb, > atl1c_tx_rollback(adapter, tpd, type); > dev_kfree_skb_any(skb); > } else { > - netdev_sent_queue(adapter->netdev, skb->len); > - atl1c_tx_queue(adapter, skb, tpd, type); > + bool more = netdev_xmit_more(); > + > + __netdev_sent_queue(adapter->netdev, skb->len, more); > + if (!more) > + atl1c_tx_queue(adapter, type); > } > > return NETDEV_TX_OK; > -- > 2.31.1 >