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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 83235C76191 for ; Wed, 24 Jul 2019 20:32:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 44BE7206DD for ; Wed, 24 Jul 2019 20:32:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564000376; bh=+E7l2ji47+QPKyzCYtnJU/gcwcZY0L7QrDYr5U6InH8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Afaae5ZYUEq/TlMwO+Tb+ntle/7rXfwe1BbpqfWz5IElueO36nOWdxWhEkDYRyyfd GmbGMLJRz6o8ILr2S8dPErMpAZ0XeZaQlx+pLUhqMDqSQlRSep3h94HMiqRb+4ETgL 67OeMitQhjfMztYlL1FRkEeOngYPHtU5LSawyVqk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388322AbfGXT2Y (ORCPT ); Wed, 24 Jul 2019 15:28:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:46550 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388233AbfGXT2V (ORCPT ); Wed, 24 Jul 2019 15:28:21 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D48B321951; Wed, 24 Jul 2019 19:28:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563996500; bh=+E7l2ji47+QPKyzCYtnJU/gcwcZY0L7QrDYr5U6InH8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CBtYh1A4Cf46UhJmYjGAQG1UhwDgmt8EjzO4TkSMfPuQxrLxHSUvg7FGlftOMTK23 8pDRHct3Z6oRzcNJkdC71kXj+ZSJ5MUk9SB3vqMrmVFF2bGw72CqmKQXrJ2LkM7Y6J hf32G2FSgdfelruvVYzZfJuDg3bS7cyQO7jgyE9I= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jason Wang , "Michael S. Tsirkin" , "David S. Miller" , Sasha Levin Subject: [PATCH 5.2 116/413] vhost_net: disable zerocopy by default Date: Wed, 24 Jul 2019 21:16:47 +0200 Message-Id: <20190724191743.595313393@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190724191735.096702571@linuxfoundation.org> References: <20190724191735.096702571@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org [ Upstream commit 098eadce3c622c07b328d0a43dda379b38cf7c5e ] 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 Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- 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 d57ebdd616d9..247e5585af5d 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -35,7 +35,7 @@ #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"); -- 2.20.1