Anyone who even mentions polling should be discounted altogether. Polling had value when you couldn't control the interrupt delays; but interrupt moderation allows you to pace the interrupts any way you like without the inefficiencies of polling.
The idea that polling uses less CPU is complete baloney; its exactly the same code as without polling. It's something else that the CPU has to do, so polling is a negative with almost any modern NIC. With intel nics you can set whatever interrupt rate you want; setting your ints/sec to whatever hz is (or whatever polling timer is used) has the same effect without having to have hacked code running in your driver. --- On Tue, 11/20/12, khatfi...@socllc.net <khatfi...@socllc.net> wrote: > From: khatfi...@socllc.net <khatfi...@socllc.net> > Subject: Re: FreeBSD boxes as a 'router'... > To: "Victor Balada Diaz" <vic...@bsdes.net> > Cc: "freebsd-...@freebsd.org" <freebsd-...@freebsd.org>, "John Fretby" > <jfre...@googlemail.com> > Date: Tuesday, November 20, 2012, 12:57 PM > One thing I have noticed is mixed > results with polling depending on the version. > > My experience with similar NICs was that polling increased > the PPS capabilities up to 7.4 but post 7.4 we have seen > most cases where polling caused either connectivity issues > or decreased overall performance. > > Now we were running full 1Gbps in our tests. With only > 140Mbps you should be able to handle this amount without > polling or additional kernel tweaks. Specifically with 9 - I > would recommend doing needed sysctl tweaks without polling > and as long as you are not receiving DDoS traffic then it > should prove perfectly stable. > > > > On Nov 20, 2012, at 11:46 AM, "Victor Balada Diaz" <vic...@bsdes.net> > wrote: > > > On Tue, Nov 20, 2012 at 03:35:13PM +0000, John Fretby > wrote: > >> Howdy all, > >> > >> We've currently got an ageing HP DL360 running as a > 'router' - it has > >> 100Mbit in/out onto our network, and has two 'bce' > NIC's providing in/out. > >> It's running quite an old version of FreeBSD (6 I > think) - but works. > >> > >> As the network gets busier we've noticed the amount > of interrupt time on it > >> is climbing (as you'd expect - i.e. esp. if many > small packets are being > >> forwarded). Many moons ago we did experiment with > this box - and enabled > >> device polling (inc. upping the HZ on the box and > recompiling the kernel > >> etc). This didn't work very well at the time > (probably because it was in > >> it's infancy) so we left it off in the end. > >> > >> If we were to replace this box, with something new > - say a SuperMicro based > >> system with two: > >> > >> Intel 82574L's (em Driver Based) > >> > >> And enable polling - is it likely to "just work" > these days? The current > >> upstream is 100Mbit, we're looking to upgrade this > to 1Gbit in, but with > >> say 200Mbit comitted on it (so shouldn't go above > 200Mbit). > >> > >> Is there anything that has to be done to enable > polling - other than > >> recompiling GENERIC to support it? - i.e. no HZ > hacks or anything needed on > >> 'modern' machines (it's a quad core Xeon). > > > > Hello John, > > > > You might find interesting to read this thread: > > > > http://lists.freebsd.org/pipermail/freebsd-current/2012-November/037590.html > > > > In short: device polling can decrease performance on > modern hardware. > > > > You might want to try upgrading to a new FreeBSD > version and tuning it somehow > > before buying a new server. More info on tuning the > network stack: > > > > http://wiki.freebsd.org/NetworkPerformanceTuning > > > > Regards. > > Victor. > > -- > > La prueba más fehaciente de que existe vida > inteligente en otros > > planetas, es que no han intentado contactar con > nosotros. > > _______________________________________________ > > freebsd-...@freebsd.org > mailing list > > http://lists.freebsd.org/mailman/listinfo/freebsd-isp > > To unsubscribe, send any mail to "freebsd-isp-unsubscr...@freebsd.org" > _______________________________________________ > freebsd-...@freebsd.org > mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-isp > To unsubscribe, send any mail to "freebsd-isp-unsubscr...@freebsd.org" _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
