From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=kh39=QH=vger.kernel.org=netdev-owner@kernel.org>
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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,
	MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 6511DC4151A
	for <netdev@archiver.kernel.org>; Thu, 31 Jan 2019 17:45:26 +0000 (UTC)
Received: from vger.kernel.org (vger.kernel.org [209.132.180.67])
	by mail.kernel.org (Postfix) with ESMTP id 3AE4520B1F
	for <netdev@archiver.kernel.org>; Thu, 31 Jan 2019 17:45:26 +0000 (UTC)
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1727147AbfAaRpZ (ORCPT <rfc822;netdev@archiver.kernel.org>);
        Thu, 31 Jan 2019 12:45:25 -0500
Received: from shards.monkeyblade.net ([23.128.96.9]:33622 "EHLO
        shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1725831AbfAaRpY (ORCPT
        <rfc822;netdev@vger.kernel.org>); Thu, 31 Jan 2019 12:45:24 -0500
Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::bf5])
        (using TLSv1 with cipher AES256-SHA (256/256 bits))
        (Client did not present a certificate)
        (Authenticated sender: davem-davemloft)
        by shards.monkeyblade.net (Postfix) with ESMTPSA id 5EEBA14F85B29;
        Thu, 31 Jan 2019 09:45:24 -0800 (PST)
Date:   Thu, 31 Jan 2019 09:45:23 -0800 (PST)
Message-Id: <20190131.094523.2248120325911339180.davem@davemloft.net>
To:     mst@redhat.com
Cc:     makita.toshiaki@lab.ntt.co.jp, jasowang@redhat.com,
        netdev@vger.kernel.org, virtualization@lists.linux-foundation.org,
        dsahern@gmail.com, hawk@kernel.org
Subject: Re: [PATCH net] virtio_net: Account for tx bytes and packets on
 sending xdp_frames
From:   David Miller <davem@davemloft.net>
In-Reply-To: <20190131101516-mutt-send-email-mst@kernel.org>
References: <1548934830-2389-1-git-send-email-makita.toshiaki@lab.ntt.co.jp>
        <20190131101516-mutt-send-email-mst@kernel.org>
X-Mailer: Mew version 6.8 on Emacs 26.1
Mime-Version: 1.0
Content-Type: Text/Plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Thu, 31 Jan 2019 09:45:24 -0800 (PST)
Sender: netdev-owner@vger.kernel.org
Precedence: bulk
List-ID: <netdev.vger.kernel.org>
X-Mailing-List: netdev@vger.kernel.org

From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Thu, 31 Jan 2019 10:25:17 -0500

> On Thu, Jan 31, 2019 at 08:40:30PM +0900, Toshiaki Makita wrote:
>> Previously virtnet_xdp_xmit() did not account for device tx counters,
>> which caused confusions.
>> To be consistent with SKBs, account them on freeing xdp_frames.
>> 
>> Reported-by: David Ahern <dsahern@gmail.com>
>> Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
> 
> Well we count them on receive so I guess it makes sense for consistency
> 
> Acked-by: Michael S. Tsirkin <mst@redhat.com>
> 
> however, I really wonder whether adding more and more standard net stack
> things like this will end up costing most of XDP its speed.
> 
> Should we instead make sure *not* to account XDP packets
> in any counters at all? XDP programs can use maps
> to do their own counting...

This has been definitely a discussion point, and something we should
develop a clear, strong, policy on.

David, Jesper, care to chime in where we ended up in that last thread
discussion this?