From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Falcon Subject: Re: [PATCH net-next] ibmvnic: Enable TSO support Date: Fri, 26 May 2017 11:11:05 -0500 Message-ID: <9ca1acdb-cc19-46d2-a0cf-1f2dc00678e6@linux.vnet.ibm.com> References: <1495679366-7149-1-git-send-email-tlfalcon@linux.vnet.ibm.com> <20170525.144626.1787511445330790842.davem@davemloft.net> <20170525.144935.732861960034229990.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, nfont@linux.vnet.ibm.com, jallen@linux.vnet.ibm.com To: David Miller Return-path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:44639 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932234AbdEZQLL (ORCPT ); Fri, 26 May 2017 12:11:11 -0400 Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v4QG8sUn124051 for ; Fri, 26 May 2017 12:11:10 -0400 Received: from e37.co.us.ibm.com (e37.co.us.ibm.com [32.97.110.158]) by mx0a-001b2d01.pphosted.com with ESMTP id 2apc2ecdmm-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 26 May 2017 12:11:10 -0400 Received: from localhost by e37.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 26 May 2017 10:11:09 -0600 In-Reply-To: <20170525.144935.732861960034229990.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On 05/25/2017 01:49 PM, David Miller wrote: > From: David Miller > Date: Thu, 25 May 2017 14:46:26 -0400 (EDT) > >> From: Thomas Falcon >> Date: Wed, 24 May 2017 21:29:26 -0500 >> >>> The feature is also enabled by a module parameter. >>> This parameter is necessary because TSO can not easily be >>> enabled or disabled in firmware without reinitializing the driver. >> Sorry, this is unacceptable. When I say no module parameters, >> I really really mean it. >> >> Users should not be burdoned with having to know a special knob for >> every driver in order to adjust what is a generic feature. >> >> You'll have to find another way to accomodate this. > Also, TSO helps without SG only because you haven't implemented > support for xmit_more in this driver to decrease the number of > doorball updates and VM enters. > > I bet if you added xmit_more support, TSO wouldn't give you much > if any performance boost if you have to linearize. > Thanks for the feedback. I'm looking into providing that support, but for the time being we would like to continue with supporting TSO, without using a module parameter this time.