Date: Fri, 14 Jun 2013 12:34:34 +0200 From: Andre Oppermann <andre@freebsd.org> To: Gleb Smirnoff <glebius@FreeBSD.org> Cc: Ermal Lu?i <eri@freebsd.org>, freebsd-net <freebsd-net@freebsd.org> Subject: Re: [PATH] ALTQ(9) codel algorithm implementation Message-ID: <51BAF1BA.8000603@freebsd.org> In-Reply-To: <20130614095125.GQ12443@FreeBSD.org> References: <CAPBZQG0XDmybC5tzchFrcf3TZC7uJ0VcKSX-cVMJ%2BsMZUUqWVg@mail.gmail.com> <20130614095125.GQ12443@FreeBSD.org>
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On 14.06.2013 11:51, Gleb Smirnoff wrote: > Ermal, > > On Mon, Jun 10, 2013 at 03:43:12PM +0200, Ermal Lu?i wrote: > E> at location [1] can be found a patch for Codel[3] algorithm implementation. > E> > E> Triggered by a mail to the mailing lists[2] of OpenBSD i completed the > E> implementation for FreeBSD. > E> > E> It allows to use codel as the single configured discipline on an interface. > E> Also it can be used as a sub discipline of existing queueing disciplines > E> already present. > E> > E> The work has been tested and confirmed working without issues in pfSense. > E> > E> Any objections on pushing this into FreeBSD? > E> > E> [1] > E> https://github.com/pfsense/pfsense-tools/blob/master/patches/RELENG_10_0/altq_codel.diff > E> [2] http://permalink.gmane.org/gmane.os.openbsd.tech/29745 > E> [3] http://www.bufferbloat.net/projects/codel/wiki > > I'm afraid we can't grow mbuf packet header with 8 bytes just to satisfy > the ALTQ codel algo, which would definitely have a limited usage among > FreeBSD users. Thus, "enqueue_time" should go into mbuf_tags(9) not into > mbuf packet header. Agreed. We don't have space for that in the mbuf header. There's some other fields that may be repurposed though, the header pointer for example which is almost entirely unused. With some updates to the TSO and Checksum offload mechanism I have in the pipeline the "header" field can be easily repurposed. Though I'm against an "obscure" ALTQ mechanism having its own mbuf header field as such. It must be a generic field that can be used by others as well. -- Andre
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