Re: upd: 7.2->8.1 & many networks trouble & flowtable

I am the main author of this paper you referenced in your email.

The main discussion and focus of my paper was on the design and work done to=
 separate L2 and L3 for both IPv4 and IPv6 to facilitate the elimination of G=
IANT lock in the networking subsystem, thus achieving high parallelism.=20

This redesign of separately managing L2 ARP/ND6 and L3 routing tables alread=
y show performance gain on multicore systems.

The flow-table enhancement is just one other component, described towards th=
e end of the paper. Yes, It is experimental and was discussed as such in the=
 paper as well as on the mailing list.=20

I did not know flow-table feature was enabled by default. I wouldn't have do=
ne so myself.

So help me understand you better: are you complaining about the general L2/L=
3 separation work, or you are angry about the flow-table enhancement in part=
icular?

cheers,

-- Qing

On Nov 24, 2010, at 1:54 AM, "Andrey Groshev" <greenx@yartv.ru> wrote:

> Hi, PPL!
>=20
> A couple of days ago decided to upgrade from 7.2-STABLE to 8.1-STABLE (amd=
64).
> By tradition, waited some pitfalls.
> But damn, not to the same degree!
>=20
> The hardware on the server:
> Motherboard: Intel SE7520JR23S
> CPU's: 2 x Xeon 3Ghz
> Ram: 4Gb
>=20
> Software used: openospfd, openbgpd, bind, and so on.
> In general, used as a boundary Router.
>=20
> Update ... and began:
> 1. The server died a few minutes after launch, not even reacting to the ke=
yboard. By issuing a warning about "em0 watchdog .....". I thought to myself=
 - broke the driver, connect the other network card. Server even stopped han=
ging.
> 2. Nearest switch does not like OSPF from the server and it shuts down a p=
ort or vlan.
> 3. openbgpd loads CPU nearly 100%.
> 4. bind does not respond, despite the fact that properly loads the CPU.
>=20
> In the end, I turned off everything that does not work as is necessary,
> Only remaining process FLOWCLEANER which can be CPU at 100%.
>=20
>=20
> Google started about this flowcleaner.
> And what happened? I found a report entitled "Optimizing the BSD Routing S=
ystem for Parallel Processing"(1). Roughly speaking, flowtable - a new appro=
ach to routing. Dividing the levels 2 and 3 can achieve more parallelism. Bu=
t in the end, due to this - to increase network performance. Ok, everything l=
ooks great!
>=20
> And now I ask: for whom all this? IMHO for example, ISP. Or, as stated in t=
he above-mentioned report:
>=20
>> >> "The main goals for redesigning the kernel routing infrastructure=20
> was to reduce the scope of the customization necessary when deriving produ=
cts from FreeBSD, and to offer a generic solution that could be an integral p=
art of the kernel." <<<
>=20
> What ultimately relevant only to the equipment is used at the ISP.
> Since the average user with its tiny routing table - it is not necessary.
> But beyond the problems begin. How long have you seen the ISP without "ful=
lview bpg"?
>=20
> But beyond the problems begin.
> Almost everywhere where it is mentioned a problem with FLOWCLEANER recomme=
nded for deletion from the kernel option FLOWTABLE.
> And one of the co-authors wrote in his blog(2):
>> >> "One oversight that come up shortly afterwards
> is that it adversely impacts performance for systems
> with many routing prefixes to a greater degree than I had expected." <<<
>=20
> How long have you seen the ISP without "fullview bpg"?
> It turns out that the technology is designed to increase network performan=
ce that most network generally kills, which implies that it is not suitable f=
or use.
> And here it is not simply included in the source tree, and is enabled by d=
efault in the GENERIC kernel!
> And do not say that there was no PR - they are (3)!
>=20
> ----
>=20
> Sorry so long sets out the main meaning of the message is this:
> Why in the kernel introduced new features, if it is good only on paper?
> May exclude this option from the GENERIC kernel?
>=20
> ----
>=20
> Links:
> 1. - http://conferences.sigcomm.org/sigcomm/2009/workshops/presto/papers/p=
37.pdf
> 2. - http://daemonflux.blogspot.com/2010/01/updates.html
> 3. - http://people.freebsd.org/~linimon/studies/prs/prs_for_tag_flowtable.=
html
>=20
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