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Date:      Tue, 20 Nov 2012 13:52:08 -0800 (PST)
From:      Barney Cordoba <barney_cordoba@yahoo.com>
To:        khatfield@socllc.net
Cc:        freebsd-net@freebsd.org
Subject:   Re: FreeBSD boxes as a 'router'...
Message-ID:  <1353448328.76219.YahooMailClassic@web121602.mail.ne1.yahoo.com>
In-Reply-To: <1281530059.17550.1353434227450@238ae4dab3b4454b88aea4d9f7c372c1.nuevasync.com>

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Anyone who even mentions polling should be discounted altogether. Polling=
=0Ahad value when you couldn't control the interrupt delays; but interrupt=
=0Amoderation allows you to pace the interrupts any way you like without=0A=
the inefficiencies of polling.=0A=0AThe idea that polling uses less CPU is =
complete baloney; its exactly=0Athe same code as without polling. It's some=
thing else that the CPU=0Ahas to do, so polling is a negative with almost a=
ny modern NIC. With=0Aintel nics you can set whatever interrupt rate you wa=
nt; setting your=0Aints/sec to whatever hz is (or whatever polling timer is=
 used) has=0Athe same effect without having to have hacked code running in =
your driver.=0A=0A--- On Tue, 11/20/12, khatfield@socllc.net <khatfield@soc=
llc.net> wrote:=0A=0A> From: khatfield@socllc.net <khatfield@socllc.net>=0A=
> Subject: Re: FreeBSD boxes as a 'router'...=0A> To: "Victor Balada Diaz" =
<victor@bsdes.net>=0A> Cc: "freebsd-isp@freebsd.org" <freebsd-isp@freebsd.o=
rg>, "John Fretby" <jfretby@googlemail.com>=0A> Date: Tuesday, November 20,=
 2012, 12:57 PM=0A> One thing I have noticed is mixed=0A> results with poll=
ing depending on the version.=0A> =0A> My experience with similar NICs was =
that polling increased=0A> the PPS capabilities up to 7.4 but post 7.4 we h=
ave seen=0A> most cases where polling caused either connectivity issues=0A>=
 or decreased overall performance.=0A> =0A> Now we were running full 1Gbps =
in our tests. With only=0A> 140Mbps you should be able to handle this amoun=
t without=0A> polling or additional kernel tweaks. Specifically with 9 - I=
=0A> would recommend doing needed sysctl tweaks without polling=0A> and as =
long as you are not receiving DDoS traffic then it=0A> should prove perfect=
ly stable.=0A> =0A> =0A> =0A> On Nov 20, 2012, at 11:46 AM, "Victor Balada =
Diaz" <victor@bsdes.net>=0A> wrote:=0A> =0A> > On Tue, Nov 20, 2012 at 03:3=
5:13PM +0000, John Fretby=0A> wrote:=0A> >> Howdy all,=0A> >> =0A> >> We've=
 currently got an ageing HP DL360 running as a=0A> 'router' - it has=0A> >>=
 100Mbit in/out onto our network, and has two 'bce'=0A> NIC's providing in/=
out.=0A> >> It's running quite an old version of FreeBSD (6 I=0A> think) - =
but works.=0A> >> =0A> >> As the network gets busier we've noticed the amou=
nt=0A> of interrupt time on it=0A> >> is climbing (as you'd expect - i.e. e=
sp. if many=0A> small packets are being=0A> >> forwarded). Many moons ago w=
e did experiment with=0A> this box - and enabled=0A> >> device polling (inc=
. upping the HZ on the box and=0A> recompiling the kernel=0A> >> etc). This=
 didn't work very well at the time=0A> (probably because it was in=0A> >> i=
t's infancy) so we left it off in the end.=0A> >> =0A> >> If we were to rep=
lace this box, with something new=0A> - say a SuperMicro based=0A> >> syste=
m with two:=0A> >> =0A> >>=A0=A0=A0Intel 82574L's (em Driver Based)=0A> >> =
=0A> >> And enable polling - is it likely to "just work"=0A> these days? Th=
e current=0A> >> upstream is 100Mbit, we're looking to upgrade this=0A> to =
1Gbit in, but with=0A> >> say 200Mbit comitted on it (so shouldn't go above=
=0A> 200Mbit).=0A> >> =0A> >> Is there anything that has to be done to enab=
le=0A> polling - other than=0A> >> recompiling GENERIC to support it? - i.e=
. no HZ=0A> hacks or anything needed on=0A> >> 'modern' machines (it's a qu=
ad core Xeon).=0A> > =0A> > Hello John,=0A> > =0A> > You might find interes=
ting to read this thread:=0A> > =0A> > http://lists.freebsd.org/pipermail/f=
reebsd-current/2012-November/037590.html=0A=0A> > =0A> > In short: device p=
olling can decrease performance on=0A> modern hardware.=0A> > =0A> > You mi=
ght want to try upgrading to a new FreeBSD=0A> version and tuning it someho=
w=0A> > before buying a new server. More info on tuning the=0A> network sta=
ck:=0A> > =0A> > http://wiki.freebsd.org/NetworkPerformanceTuning=0A=0A>; > =
=0A> > Regards.=0A> > Victor.=0A> > -- =0A> > La prueba m=E1s fehaciente de=
 que existe vida=0A> inteligente en otros=0A> > planetas, es que no han int=
entado contactar con=0A> nosotros. =0A> > _________________________________=
______________=0A> > freebsd-isp@freebsd.org=0A> mailing list=0A> > http://=
lists.freebsd.org/mailman/listinfo/freebsd-isp=0A=0A> > To unsubscribe, sen=
d any mail to "freebsd-isp-unsubscribe@freebsd.org"=0A> ___________________=
____________________________=0A> freebsd-isp@freebsd.org=0A> mailing list=
=0A> http://lists.freebsd.org/mailman/listinfo/freebsd-isp=0A>; To unsubscri=
be, send any mail to "freebsd-isp-unsubscribe@freebsd.org"



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