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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 5B3DFC31E44 for ; Fri, 14 Jun 2019 11:34:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2480F208CA for ; Fri, 14 Jun 2019 11:34:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727345AbfFNLeg (ORCPT ); Fri, 14 Jun 2019 07:34:36 -0400 Received: from s3.sipsolutions.net ([144.76.43.62]:40476 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727054AbfFNLeg (ORCPT ); Fri, 14 Jun 2019 07:34:36 -0400 Received: by sipsolutions.net with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1hbkTW-0006zw-FG; Fri, 14 Jun 2019 13:34:30 +0200 Message-ID: <2c983ef178ae8164c3cdcedb9833292c7b91a703.camel@sipsolutions.net> Subject: Re: [PATCH v3 wireless-drivers 1/3] mt76: usb: fix rx A-MSDU support From: Johannes Berg To: Stanislaw Gruszka Cc: Lorenzo Bianconi , Lorenzo Bianconi , kvalo@codeaurora.org, linux-wireless@vger.kernel.org, nbd@nbd.name Date: Fri, 14 Jun 2019 13:34:28 +0200 In-Reply-To: <20190614113120.GC17298@redhat.com> References: <66fc02e45fb5ce0d6176395b5ac43acbd53b3e66.1560461404.git.lorenzo@kernel.org> <20190614072449.GA3395@redhat.com> <20190614101115.GA2669@localhost.localdomain> <20190614113120.GC17298@redhat.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-2.fc28) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Fri, 2019-06-14 at 13:31 +0200, Stanislaw Gruszka wrote: > On Fri, Jun 14, 2019 at 12:20:59PM +0200, Johannes Berg wrote: > > On Fri, 2019-06-14 at 12:11 +0200, Lorenzo Bianconi wrote: > > > > > Looking at __ieee80211_amsdu_copy() now I got why other drivers copy hdrlen + > > > 8, thx :) > > > In our case reuse_frag is true in __ieee80211_amsdu_copy, so we will end up > > > copying 32B + ether_len. Anyway I think 32 is a little bit too low and we could get > > > better performances increasing it a little bit. > > > A typical use case (e.g IPv6 + TCP): > > > > > > IPv6 = 40B, TCP = 32B --> so 72B..I guess 128B is a good value :) > > > @Felix, Johannes: what do you think? > > > > I think while we might *allocate* more, I don't think we should *copy* > > more, since then the TCP payload will no longer be in pages. > > > > It'd probably be better to implement leaving enough tailroom (allocate > > 128), but copying nothing, unless the *entire* packet fits. > > iwl4965 put entire packet in fragment in il4965_pass_packet_to_mac80211() . > Initially I thought this is a bug, since mac80211 require header be > in the linear area, but looks like ieee80211_rx_monitor() copy header > before rest of mac80211 check it, so 4965 is fine. Mac80211 should not assume anything about header being present or not, just like the rest of the network stack. > Anyway I think the driver should put ieee80211 header in linear area > and iwlwifi & mt7601u implementation is somewhat optimal. Yes, it's just an optimisation to do the copy-break (copy small packets completely) or to copy the header already (since we may have better ways to do so than skb_copy_bits if we still have a virt pointer to the page, rather than just the page pointer). johannes