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[23.128.96.18]) by mx.google.com with ESMTP id f25si10071047eja.117.2021.03.21.17.56.52; Sun, 21 Mar 2021 17:57:14 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=mAjRKsiH; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229613AbhCVAy3 (ORCPT + 99 others); Sun, 21 Mar 2021 20:54:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43394 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229829AbhCVAyM (ORCPT ); Sun, 21 Mar 2021 20:54:12 -0400 Received: from mail-pf1-x433.google.com (mail-pf1-x433.google.com [IPv6:2607:f8b0:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1F2D1C061574; Sun, 21 Mar 2021 17:54:11 -0700 (PDT) Received: by mail-pf1-x433.google.com with SMTP id c17so2929711pfn.6; Sun, 21 Mar 2021 17:54:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=ZqTdh65re5NOM88Bvn/Ypjdea75IBIwk3x5yx/WoBHk=; b=mAjRKsiHwBtW0yF3hWXsRMbk6nXYqyDwKcILPuoELgnTAbFFFLJ4l7AfkO5Dy6mC8e vTct0XhX3cAlVrolU2tzrlFqgf7DkTXloU3xKURQbKglhtlZ7OFXJx52AfnFZwpvb/X9 gYlfrTjc58M0cKOQ7R+Ociy/5xKopHigb+fMdf+u4AEjalojcUcnBnJ9oPaJH7RM4+nZ 36ZUhq1mA4r/n87dHdGc9Vn1zISngvOIYWJAjME4EaeAUs8aj1ffVbbHhg+ZXbVooelq LsrIdWCMLt+Oyrob/4zJP53WLSKpvC1SEKqHpaoCeS+yPIKjOcooJR6/S5Ag6Tz+TdVp OvWQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=ZqTdh65re5NOM88Bvn/Ypjdea75IBIwk3x5yx/WoBHk=; b=OiSqiBLB8jnp/3L+rzN5tMTqTXRlVMDzOeamIyiRN/Fv0qpSa4XG5zhk0Wq8tc9ayI 7aToxEPFZhkHp7pU4Z1haexOytG0ndH01YIvdBKtF8C1bhlex6uDmrBGyrpSNdmJL5OL ilO/P+kEJj5WqVuHPL1BhCZsvEbgu0xDJ2yLRghIir8aNSpG/q8LElI09GTyREcP25BS eJ3dmrbv0UZ2PHsMwZYt7dRBn/G5Ft9PJOFyydZvKmD6/W7xJ9fUAhABkwb+MHvNZe9/ v6DwVJbGu1XYIT/fLxt+S/ES0mndLT95twRrahGHZgM+whcIabrIcoCbrB9PlH+JEqto HNNQ== X-Gm-Message-State: AOAM530JFtDol0dY8Kc7Pf+TGKIzHSIEq8qymYC+9ZyXYZfWcg+F0Ked uQUQ2PMwPmo/tKbygu/OtAQ= X-Received: by 2002:a62:3706:0:b029:211:3d70:a55a with SMTP id e6-20020a6237060000b02902113d70a55amr16219198pfa.16.1616374450057; Sun, 21 Mar 2021 17:54:10 -0700 (PDT) Received: from DESKTOP-8REGVGF.localdomain ([211.25.125.254]) by smtp.gmail.com with ESMTPSA id i10sm17589687pjm.1.2021.03.21.17.54.07 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Sun, 21 Mar 2021 17:54:09 -0700 (PDT) Date: Mon, 22 Mar 2021 08:54:01 +0800 From: Sieng Piaw Liew To: Willy Tarreau Cc: chris.snook@gmail.com, davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] atl1c: optimize rx loop Message-ID: <20210322005326.GA24403@DESKTOP-8REGVGF.localdomain> References: <20210319040447.527-1-liew.s.piaw@gmail.com> <20210319041535.GA3441@1wt.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210319041535.GA3441@1wt.eu> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 19, 2021 at 05:15:35AM +0100, Willy Tarreau wrote: > On Fri, Mar 19, 2021 at 12:04:47PM +0800, Sieng Piaw Liew wrote: > > Remove this trivial bit of inefficiency from the rx receive loop, > > results in increase of a few Mbps in iperf3. Tested on Intel Core2 > > platform. > > > > Signed-off-by: Sieng Piaw Liew > > --- > > drivers/net/ethernet/atheros/atl1c/atl1c_main.c | 4 +--- > > 1 file changed, 1 insertion(+), 3 deletions(-) > > > > diff --git a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c > > index 3f65f2b370c5..b995f9a0479c 100644 > > --- a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c > > +++ b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c > > @@ -1796,9 +1796,7 @@ static void atl1c_clean_rx_irq(struct atl1c_adapter *adapter, > > struct atl1c_recv_ret_status *rrs; > > struct atl1c_buffer *buffer_info; > > > > - while (1) { > > - if (*work_done >= work_to_do) > > - break; > > + while (*work_done < work_to_do) { > > It should not change anything, or only based on the compiler's optimization > and should not result in a measurable difference because what it does is > exactly the same. Have you really compared the compiled output code to > explain the difference ? I strongly suspect you'll find no difference at > all. > > Thus for me it's certainly not an optimization, it could be qualified as > a cleanup to improve code readability however. > > Willy You're right. Objdump and diff showed no difference. Regards, Sieng Piaw