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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 757C2C282DD for ; Thu, 23 May 2019 11:11:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4CCA92133D for ; Thu, 23 May 2019 11:11:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730626AbfEWLLY (ORCPT ); Thu, 23 May 2019 07:11:24 -0400 Received: from mail-ed1-f67.google.com ([209.85.208.67]:43578 "EHLO mail-ed1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728518AbfEWLLY (ORCPT ); Thu, 23 May 2019 07:11:24 -0400 Received: by mail-ed1-f67.google.com with SMTP id w33so5299804edb.10 for ; Thu, 23 May 2019 04:11:23 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=TEcYx4e8I1IBeEOAlN0GMJ9nUk33G79fZt9bS9b3jQw=; b=R7r9sepU0OIjJsvBEnxyCj9QjM9C/wujdP528ef8E1yjBTSKW7Tt/tPjXogVmZNEj9 auFIAl2Pf2T2roo+4Qhx49PAbw0Krx6zFswCI6aZpl2fR/Auzifu5IEYBUhQV09v+lwA MMQRixZDxJyg70M3eAHhSwfJf+762WIV2KS2Pa2T46To3drHHqqbmmvHSCxmzEeY6u7O PfHsBIRSCIv+zCf/DL52daNUmITEadQgRNkMDrTigCc+LtRtUV4k3YsA/wvR855p42qa 4VFkcwbkMqwJ3lNwMk3iTCcqXm9Bu+cwmZu5vEHZVDFbn3tGM7FDW1fpX85/h3J8mPPy KQPw== X-Gm-Message-State: APjAAAXN6IT5MT9GVeHJz50VJ0H+bOVT5N/AlZQ2BOUIS78w+JXVMoxj AZnnZqyktTroMdUflKPXTRyUFw== X-Google-Smtp-Source: APXvYqzVQN2E/n7NMyN+o7d/FeA07G5C5giBp7Fy4y1Q2TrCQUrXc3jEJ0axiPSawB/9FYlrw10fug== X-Received: by 2002:a50:a389:: with SMTP id s9mr95264723edb.113.1558609882589; Thu, 23 May 2019 04:11:22 -0700 (PDT) Received: from alrua-x1.borgediget.toke.dk (borgediget.toke.dk. [85.204.121.218]) by smtp.gmail.com with ESMTPSA id 26sm4272690ejy.78.2019.05.23.04.11.21 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 23 May 2019 04:11:21 -0700 (PDT) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id E4AEC1800B1; Thu, 23 May 2019 13:11:20 +0200 (CEST) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Toshiaki Makita , Alexei Starovoitov , Daniel Borkmann , "David S. Miller" , Jakub Kicinski , Jesper Dangaard Brouer , John Fastabend Cc: Toshiaki Makita , netdev@vger.kernel.org, xdp-newbies@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH bpf-next 1/3] xdp: Add bulk XDP_TX queue In-Reply-To: <1558609008-2590-2-git-send-email-makita.toshiaki@lab.ntt.co.jp> References: <1558609008-2590-1-git-send-email-makita.toshiaki@lab.ntt.co.jp> <1558609008-2590-2-git-send-email-makita.toshiaki@lab.ntt.co.jp> X-Clacks-Overhead: GNU Terry Pratchett Date: Thu, 23 May 2019 13:11:20 +0200 Message-ID: <8736l52zon.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Toshiaki Makita writes: > XDP_TX is similar to XDP_REDIRECT as it essentially redirects packets to > the device itself. XDP_REDIRECT has bulk transmit mechanism to avoid the > heavy cost of indirect call but it also reduces lock acquisition on the > destination device that needs locks like veth and tun. > > XDP_TX does not use indirect calls but drivers which require locks can > benefit from the bulk transmit for XDP_TX as well. XDP_TX happens on the same device, so there's an implicit bulking happening because of the NAPI cycle. So why is an additional mechanism needed (in the general case)? -Toke