From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-x22b.google.com (mail-ob0-x22b.google.com [IPv6:2607:f8b0:4003:c01::22b]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 9197121F1C0 for ; Tue, 23 Apr 2013 23:14:17 -0700 (PDT) Received: by mail-ob0-f171.google.com with SMTP id er7so1182279obc.30 for ; Tue, 23 Apr 2013 23:14:16 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:x-received:x-originating-ip:in-reply-to:references :date:message-id:subject:from:to:cc:content-type:x-gm-message-state; bh=O/DXcSR3v5Ga89qCpGeNc4bB5tAlCkDZkSvITTy9Vkg=; b=VH/hhyC4aEJhELp/t6YYlJ/IAzttiu2IENhAl8TyC7L96i3EDnJOwUp7NgyzhVk6+T ogfHLJRHsTikZOurKX1x1GxLSA1gUqas/nPHhWifLGHh8mfZL/Y5VOHUW+KC1ucYmDB6 3zhkNOLtc8aDunI9luFf9DsQ/LI34b3gyc9nSBzJWi2Dhl4t4op7ukawZwyNufmydRo3 pU2naUq2bCl1MXMHlhFqFavHr4RMTFo4PTEcBrTOZecvz2Tmj6VhUo2ma7SZWqpSrF1c XxBtIxTT+ZFsHU9gYos0WTr3L1eAuZ8dwdp7lglPvVRd5HxbayWMFK6SVzrzERIesY0m 7JFw== MIME-Version: 1.0 X-Received: by 10.60.94.9 with SMTP id cy9mr13271154oeb.58.1366784056614; Tue, 23 Apr 2013 23:14:16 -0700 (PDT) Received: by 10.76.120.131 with HTTP; Tue, 23 Apr 2013 23:14:15 -0700 (PDT) X-Originating-IP: [88.128.80.7] Received: by 10.76.120.131 with HTTP; Tue, 23 Apr 2013 23:14:15 -0700 (PDT) In-Reply-To: References: Date: Wed, 24 Apr 2013 13:14:15 +0700 Message-ID: From: Maciej Soltysiak To: Dave Taht Content-Type: multipart/alternative; boundary=089e01229a902e3bdc04db1536d5 X-Gm-Message-State: ALoCoQmhNCX+L79bsnJj5GYz7ZKan1Hv/bcXsRDiO+V8NJ5kTQRUajjVde0qF18FLFzv4h6CmRtG Cc: Juliusz Chroboczek , cerowrt-devel@lists.bufferbloat.net Subject: Re: [Cerowrt-devel] atomic route updates? X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 24 Apr 2013 06:14:18 -0000 --089e01229a902e3bdc04db1536d5 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable I think I remember to fix ssdp you brought some of route cache and igmp back. Do we know if cero routed setup without route cache can work with ssdp? I wouldn't like to force bringing back route cache just for ssdp. I'm OK to test this scenario. Maciej On 20 Apr 2013 18:01, "Dave Taht" wrote: > iproute2's ip/iproute2.c code has a function called iproute_modify, > which to a blurring eye appears to be capable of doing an atomic route > update via it's netlink interface. > > " if (matches(*argv, "change") =3D=3D 0 || strcmp(*argv, "chg") = =3D=3D 0) > return iproute_modify(RTM_NEWROUTE, NLM_F_REPLACE, > argc-1, argv+1); > if (matches(*argv, "replace") =3D=3D 0) > return iproute_modify(RTM_NEWROUTE, > NLM_F_CREATE|NLM_F_REPLACE, > argc-1, argv+1);" > > The babel native daemon and the quagga-re code, however, does a > delete/add, which results in packets dropping on the floor when a > route changes. > > Everyone that's tried to make this code do atomic updates has failed. > > Juliusz thinks this section of the codebase is cursed, and I > personally, gave up, because dave miller had spent most of the last 3+ > years eliminating the linux kernel route cache, (which was finally > eliminated a few kernel versions back (3.6?)) and I figured all > attempts at doing anything fancy with routing during that phase was > going to break in odd ways until the new cache-free-linux-kernel > routing code stabilized. > > OK, so, like, it's kernel 3.8 time now, and ... I find myself too > scarred by previous attempts to give it a go myself, but I know that > out there are intrepid explorers out there, just dying to delve into > the gnarly details of netlink programming to keep a few more streams > going full throttle in the face of a routing change! Yes? Anyone? So > take a look at iproute2 and the relevant netlink code here: > > git://github.com/Quagga-RE/quagga-RE.git > git://github.com/jech/babeld.git > > I note that I have a few other ideas for netlink-related changes to > cero. Two of the big ones is that I'd like to be able to have a > userspace daemon get back more details as to when *fq_codel drops a > packet (e.g, send a multicast to a listener of the dropped the packet, > and why), and get some sort of ongoing bandwidth estimate when it > starts dropping, etc. > > I also have some hope for multi-prefix multi-homed routing too... > > but I find netlink really intimidating. It has an interface that only > a bit-banger would love. > > -- > Dave T=C3=A4ht > > PS: I have a build of 3.8.8 at the moment that uses the new PROCD > replacement for init that I'm losing a battle on, too. Also toke has > got cero mostly independently buildable now. > > Fixing bufferbloat with cerowrt: > http://www.teklibre.com/cerowrt/subscribe.html > _______________________________________________ > Cerowrt-devel mailing list > Cerowrt-devel@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cerowrt-devel > --089e01229a902e3bdc04db1536d5 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

I think I remember to fix ssdp you brought some of route cac= he and igmp back. Do we know if cero routed setup without route cache can w= ork with ssdp? I wouldn't like to force bringing back route cache just = for ssdp.

I'm OK to test this scenario.

Maciej

On 20 Apr 2013 18:01, "Dave Taht" <= dave.taht@gmail.com> wrote:
iproute2's ip/iproute2.c code has a function called iproute_modify,
which to a blurring eye appears to be capable of doing an atomic route
update via it's netlink interface.

" =C2=A0 =C2=A0 =C2=A0 =C2=A0if (matches(*argv, "change") = =3D=3D 0 || strcmp(*argv, "chg") =3D=3D 0)
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 return iproute_modi= fy(RTM_NEWROUTE, NLM_F_REPLACE,
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 argc-1, argv+1)= ;
=C2=A0 =C2=A0 =C2=A0 =C2=A0 if (matches(*argv, "replace") =3D=3D = 0)
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 return iproute_modi= fy(RTM_NEWROUTE, NLM_F_CREATE|NLM_F_REPLACE,
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 argc-1, argv+1)= ;"

The babel =C2=A0native daemon and the quagga-re code, however, does a
delete/add, which results in packets dropping on the floor when a
route changes.

Everyone that's tried to make this code do atomic updates has failed.
Juliusz thinks this section of the codebase is cursed, and I
personally, gave up, because dave miller had spent most of the last 3+
years eliminating the linux kernel route cache, (which was finally
eliminated a few kernel versions back (3.6?)) and I figured all
attempts at doing anything fancy with routing during that phase was
going to break in odd ways until the new cache-free-linux-kernel
routing code stabilized.

OK, so, like, it's kernel 3.8 time now, and ... =C2=A0I find myself too=
scarred by previous attempts to give it a go myself, but I know that
out there are intrepid explorers out there, just dying to delve into
the gnarly details of netlink programming to keep a few more streams
going full throttle in the face of a routing change! Yes? Anyone? So
take a look at iproute2 and the relevant netlink code here:

git://github.com/Quagga-RE/quagga-RE.git
git://githu= b.com/jech/babeld.git

I note that I have a few other ideas for netlink-related changes to
cero. Two of the big ones is that I'd like to be able to have a
userspace daemon get back more details as to when *fq_codel drops a
packet (e.g, send a multicast to a listener of the dropped the packet,
and why), and get some sort of ongoing bandwidth estimate when it
starts dropping, etc.

I also have some hope for multi-prefix multi-homed routing too...

but I find netlink really intimidating. It has an interface that only
a bit-banger would love.

--
Dave T=C3=A4ht

PS: I have a build of 3.8.8 at the moment that uses the new PROCD
replacement for init that I'm losing a battle on, too. Also toke has got cero mostly independently buildable now.

Fixing bufferbloat with cerowrt: http://www.teklibre.com/cerowrt/subscrib= e.html
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