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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT 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 122BAC31E46 for ; Wed, 12 Jun 2019 14:21:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DBB6220866 for ; Wed, 12 Jun 2019 14:21:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2409318AbfFLOVj (ORCPT ); Wed, 12 Jun 2019 10:21:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50452 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2409256AbfFLOVj (ORCPT ); Wed, 12 Jun 2019 10:21:39 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DED113097053; Wed, 12 Jun 2019 14:21:33 +0000 (UTC) Received: from localhost (unknown [10.40.205.188]) by smtp.corp.redhat.com (Postfix) with ESMTP id 724EB1001B10; Wed, 12 Jun 2019 14:21:30 +0000 (UTC) Date: Wed, 12 Jun 2019 16:21:29 +0200 From: Stanislaw Gruszka To: Lorenzo Bianconi Cc: Lorenzo Bianconi , nbd@nbd.name, kvalo@codeaurora.org, linux-wireless@vger.kernel.org Subject: Re: [PATCH v2 2/2] mt76: usb: do not always copy the first part of received frames Message-ID: <20190612142128.GA20760@redhat.com> References: <2ed0b595a12944a8cfea14e066bcc4fa24f0ba44.1559293385.git.lorenzo@kernel.org> <20190612091036.GB2965@redhat.com> <20190612095302.GD8107@localhost.localdomain> <20190612102502.GB4431@redhat.com> <20190612104921.GF8107@localhost.localdomain> <20190612115120.GA3496@redhat.com> <20190612122845.GH8107@localhost.localdomain> <20190612125905.GB2600@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190612125905.GB2600@redhat.com> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Wed, 12 Jun 2019 14:21:39 +0000 (UTC) Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Wed, Jun 12, 2019 at 02:59:05PM +0200, Stanislaw Gruszka wrote: > > > If max RX AMSDU size is 3839B I do not see reason why we allocate > > > MT_SG_MAX_SIZE=8 of MT_RX_BUF_SIZE=2k buffers for sg_en case. > > > I thought the reason is that max AMSDU size is 16kB so it fit into > > > 8 sg buffers of 2k. > > > > > > In other words, for me, looks like either > > > - we can not handle AMSDU for non sg case because we do not > > > allocate big enough buffer > > > > I think AMSDU is mandatory and we currently support it even for non-sg case > > (since max rx AMSDU is 3839B) > > > > > or > > > - we can just use one PAGE_SIZE buffer for rx and remove sg > > > buffers for rx completely > > > > using sg buffers we can support bigger rx AMSDU size in the future without using > > huge buffers (e.g. we can try to use IEEE80211_MAX_MPDU_LEN_HT_7935 with > > mt76x2u) > > I think it would be simpler just to allocate 2 pages for 7935B . And if we could determine that there is no true need to use sg for rx, I think best approach here would be revert f8f527b16db5 in v5.2 to fix regression and remove rx sg in -next. That would make code simpler, allocate 4k instead 16k per packet, allow to use build_skb (4096 - 3839 give enough space for shared info) and not use usb hcd bounce buffer. Stanislaw