From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751292AbdBCP62 (ORCPT ); Fri, 3 Feb 2017 10:58:28 -0500 Received: from mail-wm0-f66.google.com ([74.125.82.66]:32953 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750924AbdBCP60 (ORCPT ); Fri, 3 Feb 2017 10:58:26 -0500 Date: Fri, 3 Feb 2017 16:58:22 +0100 From: Corentin Labbe To: David Miller Cc: peppe.cavallaro@st.com, alexandre.torgue@st.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 13/17] net: stmmac: Implement NAPI for TX Message-ID: <20170203155822.GD3653@Red> References: <20170131091152.13842-14-clabbe.montjoie@gmail.com> <20170131.231225.59679013563845652.davem@davemloft.net> <20170203134145.GB3653@Red> <20170203.101530.2022314159293725201.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170203.101530.2022314159293725201.davem@davemloft.net> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 03, 2017 at 10:15:30AM -0500, David Miller wrote: > From: Corentin Labbe > Date: Fri, 3 Feb 2017 14:41:45 +0100 > > > On Tue, Jan 31, 2017 at 11:12:25PM -0500, David Miller wrote: > >> From: Corentin Labbe > >> Date: Tue, 31 Jan 2017 10:11:48 +0100 > >> > >> > The stmmac driver run TX completion under NAPI but without checking > >> > the work done by the TX completion function. > >> > >> The current behavior is correct and completely intentional. > >> > >> A driver should _never_ account TX work to the NAPI poll budget. > >> > >> This is because TX liberation is orders of magnitude cheaper than > >> receiving a packet, and such SKB freeing makes more SKBs available > >> for RX processing. > >> > >> Therefore, TX work should never count against the NAPI budget. > >> > >> Please do not fix something which is not broken. > > > > So at least the documentation I read must be fixed (https://wiki.linuxfoundation.org/networking/napi) > > We have no control over nor care about what the Linux Foundation writes > about the Linux networking code. > > Complain to them and please do not bother us about it. > > Thank you. Sorry, this was not to bother you. Could you give me your opinion on the other question of the mail ? (just copied below) So perhaps the best way is to do like intel igb/ixgbe, keeping under NAPI until the stmmac_tx_clean function said that it finished handling the queue (with a distinct TX budget)? Thanks Regards