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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 C13AEC31E5B for ; Mon, 17 Jun 2019 14:43:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 95F2620833 for ; Mon, 17 Jun 2019 14:43:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728438AbfFQOnP (ORCPT ); Mon, 17 Jun 2019 10:43:15 -0400 Received: from mail-qt1-f196.google.com ([209.85.160.196]:41010 "EHLO mail-qt1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727997AbfFQOnP (ORCPT ); Mon, 17 Jun 2019 10:43:15 -0400 Received: by mail-qt1-f196.google.com with SMTP id d17so6010889qtj.8 for ; Mon, 17 Jun 2019 07:43:15 -0700 (PDT) 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; bh=lxS/dzQw4wkh+Z+PAMdqgR2Kw5xVW/ETkqpwQQdohjY=; b=uOiPQVSvdji650lqSVqMSA9lqtVjZlLs4sXfwABm+f4Lc0DO9TO4rYr8XIoijxtblQ zedBfwurkpj8zF5uIxhRRZwUZEd/1shsuQ8aE7b9bGuuxvUcR+Wrs5dQYLnZqy4B485i KwMLg7E+ZnTNzNr/kYPyW9xFbVHr4oMNdZmOMOVcs5IK7MHayx+KgKxM6TwXrkVZqkmz z1aELK1gidoPgWjzfAUMen540inm6WttYgOeopnAe9tgY7wgheL/m1fg0go4kWymDLqM xpWn7EPGbK7ZoUHJyEDjECQn3O0fcpkeeE2vnGyOcQAyntDZLfTg+20I0rKY+5WM0ID6 ArpA== X-Gm-Message-State: APjAAAWLnw/lb08Pim9v7JWp59RUSKDVGDg4r0YboM/sDfB7X8kXD/xV neyeyoGlrGZ7l8vR/IiR4XsyUNFKy/4= X-Google-Smtp-Source: APXvYqwavvGjRNDaa71vDWp/7KVZgO3Ghhc2s0zA1b8b++lVdLmzk98FDf0R90PixvOg24leSYkxow== X-Received: by 2002:a0c:b5dd:: with SMTP id o29mr21771848qvf.85.1560782594646; Mon, 17 Jun 2019 07:43:14 -0700 (PDT) Received: from redhat.com (pool-100-0-197-103.bstnma.fios.verizon.net. [100.0.197.103]) by smtp.gmail.com with ESMTPSA id s44sm8410210qtc.8.2019.06.17.07.43.13 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 17 Jun 2019 07:43:13 -0700 (PDT) Date: Mon, 17 Jun 2019 10:43:12 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, huhai@kylinos.cn Subject: Re: [PATCH net-next] vhost_net: disable zerocopy by default Message-ID: <20190617104301-mutt-send-email-mst@kernel.org> References: <20190617092054.12299-1-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190617092054.12299-1-jasowang@redhat.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Jun 17, 2019 at 05:20:54AM -0400, Jason Wang wrote: > Vhost_net was known to suffer from HOL[1] issues which is not easy to > fix. Several downstream disable the feature by default. What's more, > the datapath was split and datacopy path got the support of batching > and XDP support recently which makes it faster than zerocopy part for > small packets transmission. > > It looks to me that disable zerocopy by default is more > appropriate. It cold be enabled by default again in the future if we > fix the above issues. > > [1] https://patchwork.kernel.org/patch/3787671/ > > Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin > --- > drivers/vhost/net.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c > index 2d9df786a9d3..21e0805e5e60 100644 > --- a/drivers/vhost/net.c > +++ b/drivers/vhost/net.c > @@ -36,7 +36,7 @@ > > #include "vhost.h" > > -static int experimental_zcopytx = 1; > +static int experimental_zcopytx = 0; > module_param(experimental_zcopytx, int, 0444); > MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;" > " 1 -Enable; 0 - Disable"); > -- > 2.18.1