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Date:      Sun, 3 May 2015 16:17:29 +0000 (UTC)
From:      Barney Cordoba <barney_cordoba@yahoo.com>
To:        "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>
Subject:   Re: Fwd: netmap-ipfw on em0 em1
Message-ID:  <1574363412.546978.1430669849590.JavaMail.yahoo@mail.yahoo.com>
In-Reply-To: <CAGQ6iC8NZgNW%2BE1wtap-A7ihchDQQ5L3w=VdRCDFXy9%2BtgExWg@mail.gmail.com>
References:  <CAGQ6iC8NZgNW%2BE1wtap-A7ihchDQQ5L3w=VdRCDFXy9%2BtgExWg@mail.gmail.com>

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Frankly I'm baffled by netmap. You can easily write a loadable kernel module that moves packets from 1 interface to another and hook in the firewall; why would you want to bring them up into user space? It's 1000s of lines of unnecessary code.
 



     On Sunday, May 3, 2015 3:10 AM, Raimundo Santos <raitech@gmail.com> wrote:
   

 Clarifying things for the sake of documentation:

To use the host stack, append a ^ character after the name of the interface
you want to use. (Info from netmap(4) shipped with FreeBSD 10.1 RELEASE.)

Examples:

"kipfw em0" does nothing useful.
"kipfw netmap:em0" disconnects the NIC from the usual data path, i.e.,
there are no host communications.
"kipfw netmap:em0 netmap:em0^" or "kipfw netmap:em0+" places the
netmap-ipfw rules between the NIC and the host stack entry point associated
(the IP addresses configured on it with ifconfig, ARP and RARP, etc...)
with the same NIC.

On 10 November 2014 at 18:29, Evandro Nunes <evandronunes12@gmail.com>
wrote:

> dear professor luigi,
> i have some numbers, I am filtering 773Kpps with kipfw using 60% of CPU and
> system using the rest, this system is a 8core at 2.4Ghz, but only one core
> is in use
> in this next round of tests, my NIC is now an avoton with igb(4) driver,
> currently with 4 queues per NIC (total 8 queues for kipfw bridge)
> i have read in your papers we should expect something similar to 1.48Mpps
> how can I benefit from the other CPUs which are completely idle? I tried
> CPU Affinity (cpuset) kipfw but system CPU usage follows userland kipfw so
> I could not set one CPU to userland while other for system
>

All the papers talk about *generating* lots of packets, not *processing*
lots of packets. What this netmap example does is processing. If someone
really wants to use the host stack, the expected performance WILL BE worse
- what's the point of using a host stack bypassing tool/framework if
someone will end up using the host stack?

And by generating, usually the papers means: minimum sized UDP packets.


>
> can you please enlighten?
>

For everyone: read the manuals, read related and indicated materials
(papers, web sites, etc), and, as a least resource, read the code. Within
netmap's codes, it's more easy than it sounds.
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Subject: Re: Fwd: netmap-ipfw on em0 em1
From: Luigi Rizzo <rizzo@iet.unipi.it>
To: Barney Cordoba <barney_cordoba@yahoo.com>
Cc: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>
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On Sun, May 3, 2015 at 6:17 PM, Barney Cordoba via freebsd-net <
freebsd-net@freebsd.org> wrote:

> Frankly I'm baffled by netmap. You can easily write a loadable kernel
> module that moves packets from 1 interface to another and hook in the
> firewall; why would you want to bring them up into user space? It's 1000s
> of lines of unnecessary code.
>
>
Because it is much faster.

The motivation for netmap-like
solutions (that includes Intel's DPDK, PF_RING/DNA
and several proprietary implementations) is speed:
they bypass the entire network stack, and a
good part of the device drivers, so you can access
packets 

10+ times faster.
So things are actually the other way around:
the 1000's of unnecessary
lines of code
(not really thousands, though)
are
those that you'd pay going through the standard
network stack
when you
don't need any of its services.

Going to userspace is just a side effect -- turns out to
be easier to develop and run your packet processing code
in userspace, but there are netmap clients (e.g. the
VALE software switch) which run entirely in the kernel.

cheers
luigi



>
>
>      On Sunday, May 3, 2015 3:10 AM, Raimundo Santos <raitech@gmail.com>
> wrote:
>
>
>  Clarifying things for the sake of documentation:
>
> To use the host stack, append a ^ character after the name of the interface
> you want to use. (Info from netmap(4) shipped with FreeBSD 10.1 RELEASE.)
>
> Examples:
>
> "kipfw em0" does nothing useful.
> "kipfw netmap:em0" disconnects the NIC from the usual data path, i.e.,
> there are no host communications.
> "kipfw netmap:em0 netmap:em0^" or "kipfw netmap:em0+" places the
> netmap-ipfw rules between the NIC and the host stack entry point associated
> (the IP addresses configured on it with ifconfig, ARP and RARP, etc...)
> with the same NIC.
>
> On 10 November 2014 at 18:29, Evandro Nunes <evandronunes12@gmail.com>
> wrote:
>
> > dear professor luigi,
> > i have some numbers, I am filtering 773Kpps with kipfw using 60% of CPU
> and
> > system using the rest, this system is a 8core at 2.4Ghz, but only one
> core
> > is in use
> > in this next round of tests, my NIC is now an avoton with igb(4) driver,
> > currently with 4 queues per NIC (total 8 queues for kipfw bridge)
> > i have read in your papers we should expect something similar to 1.48Mpps
> > how can I benefit from the other CPUs which are completely idle? I tried
> > CPU Affinity (cpuset) kipfw but system CPU usage follows userland kipfw
> so
> > I could not set one CPU to userland while other for system
> >
>
> All the papers talk about *generating* lots of packets, not *processing*
> lots of packets. What this netmap example does is processing. If someone
> really wants to use the host stack, the expected performance WILL BE worse
> - what's the point of using a host stack bypassing tool/framework if
> someone will end up using the host stack?
>
> And by generating, usually the papers means: minimum sized UDP packets.
>
>
> >
> > can you please enlighten?
> >
>
> For everyone: read the manuals, read related and indicated materials
> (papers, web sites, etc), and, as a least resource, read the code. Within
> netmap's codes, it's more easy than it sounds.
> _______________________________________________
> freebsd-net@freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-net
> To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
>
>
>
> _______________________________________________
> freebsd-net@freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-net
> To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
>



-- 
-----------------------------------------+-------------------------------
 Prof. Luigi RIZZO, rizzo@iet.unipi.it  . Dip. di Ing. dell'Informazione
 http://www.iet.unipi.it/~luigi/        . Universita` di Pisa
 TEL      +39-050-2217533               . via Diotisalvi 2
 Mobile   +39-338-6809875               . 56122 PISA (Italy)
-----------------------------------------+-------------------------------



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