From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.toke.dk (mail.toke.dk [IPv6:2001:470:dc45:1000::1]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id C60993B29E for ; Thu, 3 May 2018 08:40:49 -0400 (EDT) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=toke.dk; s=20161023; t=1525351247; bh=klwS9ZPjhHlUJCCZTW5caN2y7LCcqvJclZEjdmVdHJc=; h=From:To:Subject:In-Reply-To:References:Date:From; b=bN+hKMzKgxqZSc67EskyPUpn1T3xXphg0AleVNHptm2vttQr0pA3o66XLZ45z+Ey7 Y7P7CDmNGCRXtR/aU63Ut0inQ+tWZ/Z45RATqgzDViRTfE7JfK1/uv9kWbYs4/d+mP 8vWxobzkr1Gn6ujmUNWk3CAH9cXCJtabAutzBCNS4rdRKO6W6nInslCmG2Z4wfw0H0 Xvx99dMcy4T/WJMuFkJBo6/mi0Rbv1G1xj/zPMUvJ+DWJHFVL+Tso20azZcmrqAx2t xhxPvaBCSPj81/ISSsTZp/P649+1A+peKs9BDYC+yhUkntOHIMy79sEZ1lbCMFZmFl XrvBNmvJAsXFw== To: cake@lists.bufferbloat.net In-Reply-To: <201805031629.vXyGm7Ql%fengguang.wu@intel.com> References: <152527387324.14936.10258520847821060114.stgit@alrua-kau> <201805031629.vXyGm7Ql%fengguang.wu@intel.com> Date: Thu, 03 May 2018 14:40:47 +0200 X-Clacks-Overhead: GNU Terry Pratchett Message-ID: <87po2czzcg.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Cake] [PATCH net-next v7 3/7] sch_cake: Add optional ACK filter X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 03 May 2018 12:40:50 -0000 kbuild test robot writes: > Hi Toke, > > Thank you for the patch! Perhaps something to improve: > > [auto build test WARNING on net-next/master] > > url: https://github.com/0day-ci/linux/commits/Toke-H-iland-J-rgensen/sched-Add-Common-Applications-Kept-Enhanced-cake-qdisc/20180503-073002 > > > coccinelle warnings: (new ones prefixed by >>) > >>> net/sched/sch_cake.c:1047:6-13: ERROR: PTR_ERR applied after >>>initialization to constant on line 822 While attempting to fix this I realised that I didn't fully understand the complex state keeping logic in the ACK filter. And rather than try to do that, I thought I'd see what the simplest possible filter looks like. So lo and behold: https://github.com/dtaht/sch_cake/commit/df5d38a0a38ffb35c7c18e2269ac73792267bd0e This has the advantage of removing about a hundred lines of code, and being way easier to follow (and thus review). And I think it still does the right thing. The drawback is that it will loop from the head of the queue every time it is invoked rather than try to "keep its place" as the old version did. I'm honestly not sure whether the efficiency gains are worth the complex logic; we only gain something if there are both ACKs and non-ACKs in the same queue. Of course, if we *are* going to keep the old version, someone else is going to step up to fix the warning above :) What do you guys think? -Toke