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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 165AEC433EF for ; Sun, 3 Oct 2021 08:06:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E20C961B40 for ; Sun, 3 Oct 2021 08:06:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229846AbhJCIHq (ORCPT ); Sun, 3 Oct 2021 04:07:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40652 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229785AbhJCIHp (ORCPT ); Sun, 3 Oct 2021 04:07:45 -0400 Received: from mail-ed1-x535.google.com (mail-ed1-x535.google.com [IPv6:2a00:1450:4864:20::535]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BDC83C0613EC for ; Sun, 3 Oct 2021 01:05:58 -0700 (PDT) Received: by mail-ed1-x535.google.com with SMTP id g7so51013674edv.1 for ; Sun, 03 Oct 2021 01:05:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=nftDd/VZBjRt+xb7Lvr+SgeXmDg+7RLGPv63rB/K664=; b=WKUOBtR5nOhAKaBB1a8tHf+uJ/N0es90F16HEzEqPgxTv/ytFq4mztI55okXFJWHPb kfaDFC95cBQTIfM57m/74DICwGVOKIXg6+IV0dyxRi4WfohxL5qJ1PSF0zmJa29CacCE soA28E+GAIWJaTRmr4sug4c8X5MCDZ/fzCGS+pTQMMoacJNCILVCzEGo2TME4/5RMz25 RRtIerh9I8EPvi7nu4A2WlV2Y5CYdd2T5owjmCb+Rs5jd9lHHZ4UjRucUMSHnH3HvJj9 VqNMi4ntphx1AHEMjbbfNz3jK8Anvfu4hFPL28WSwTGTKojhRXhNfa+bsWSNkicGrdBw PjIQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=nftDd/VZBjRt+xb7Lvr+SgeXmDg+7RLGPv63rB/K664=; b=7KRCXYeQCehUm/mf3xFg1Q/NYMTkbtEPBw9yuCb2LqDA4wHnze67rHbz40cJKprgNe X6EFYLlBfyyMAd8xFHHLTS7Z3kutvtuX9LcUW8ljX8naPtr63L6obiWr9RWNHz0yx6HY OrApey1kewM+0qwA11cLoH9/cJHnGPh+K8fYy4juT2YRUJAkif0wwKqKjUK4nCaVTdqh CdBFkD01fGIi5B0wOgM3KoCN4058NZRCao6XYSwXV591uQqy7A7egmRK3Bz7kjbS5xPB xO2U1xEDy52V8lxg3IBkGg9zn6PZZ8iGlEJxNi8cec93DkNHyzBbswhty2/Kf8rQHQe6 XYmQ== X-Gm-Message-State: AOAM53331ozUA26VjCoI8PGzAuMdQ9Evw3OjqIycgsMUqvQDRflhF5uq GLmALWhwPaNxm9vLFWKddRM= X-Google-Smtp-Source: ABdhPJxQgfGpt1XjE9ndFs7MCC/RAaOf7ysEIty1CVwAqdKJFBvvggHzh7+WmQBJF/A2z2sbPVmuSg== X-Received: by 2002:a17:906:318b:: with SMTP id 11mr9453012ejy.493.1633248357283; Sun, 03 Oct 2021 01:05:57 -0700 (PDT) Received: from [192.168.0.108] ([176.228.98.2]) by smtp.gmail.com with ESMTPSA id j14sm5610563edl.21.2021.10.03.01.05.55 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 03 Oct 2021 01:05:56 -0700 (PDT) Subject: Re: [PATCH V2 net-next] net/mlx4_en: avoid one cache line miss to ring doorbell To: Eric Dumazet , "David S . Miller" , Jakub Kicinski Cc: netdev , Eric Dumazet , Tariq Toukan References: <20211001005249.3945672-1-eric.dumazet@gmail.com> From: Tariq Toukan Message-ID: Date: Sun, 3 Oct 2021 11:05:54 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20211001005249.3945672-1-eric.dumazet@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 10/1/2021 3:52 AM, Eric Dumazet wrote: > From: Eric Dumazet > > This patch caches doorbell address directly in struct mlx4_en_tx_ring. > > This removes the need to bring in cpu caches whole struct mlx4_uar > in fast path. > > Note that mlx4_uar is not guaranteed to be on a local node, > because mlx4_bf_alloc() uses a single free list (priv->bf_list) > regardless of its node parameter. > > This kind of change does matter in presence of light/moderate traffic. > In high stress, this read-only line would be kept hot in caches. > > Signed-off-by: Eric Dumazet > Cc: Tariq Toukan > --- > V2: added __iomem attribute to remove sparse errors (Jakub) > > drivers/net/ethernet/mellanox/mlx4/en_tx.c | 4 ++-- > drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 1 + > 2 files changed, 3 insertions(+), 2 deletions(-) > Thanks for your patch. Reviewed-by: Tariq Toukan