Date: Thu, 20 Jul 2006 21:26:13 +1000 From: Peter Jeremy <peterjeremy@optushome.com.au> To: Ed Maste <emaste@phaedrus.sandvine.ca> Cc: freebsd-stable@freebsd.org Subject: Re: How to setup polling on 'bge' interface Message-ID: <20060720112613.GB716@turion.vk2pj.dyndns.org> In-Reply-To: <20060720023856.GA65960@sandvine.com> References: <20060711190908.GC69272@registro.br> <20060720023856.GA65960@sandvine.com>
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--hHWLQfXTYDoKhP50 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, 2006-Jul-19 22:38:56 -0400, Ed Maste wrote: >- You may have to adjust some parameters in the kern.polling sysctl > tree - specifically, kern.polling.burst_max, kern.polling.each_burst > and kern.polling.user_frac might need tweaking. Note that increasing kern.polling.burst_max and kern.polling.each_burst will also increase the number of soft interrupts. >- The polling feedback algorithm does not work very well if your > workload is focused largely on per-packet tasks (such as routing or > bridging). You'll find that there is still idle CPU time at the > point you start dropping packets. I have some work in progress to > address this, but it's not yet committed. I thought setting kern.polling.idle_poll would allow the CPU to utilise all idle time. The downside is that the system always shows as 100% utilised so it's very difficult to know how busy the system actually is. >- Polling's major advantage is the avoidance of livelock on UP systems, > and not improved performance. The limited testing I've done on a Sun V20z at work suggests that you can get better routing throughput in interrupt mode than polling mode. YMMV and this is before tweaking the polling parameters. (My testing also suggests that I don't really need to do any tweaking because the limiting factor is the gigabit interfaces rather than the V20z). --=20 Peter Jeremy --hHWLQfXTYDoKhP50 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.4 (FreeBSD) iD8DBQFEv2hU/opHv/APuIcRAsTAAJ9y5Z/S9h8+yljhGeqhkQ9fWUjJ+gCgjKaC 5hdp6wCuG2qeQwc15NJ2Mb4= =shpx -----END PGP SIGNATURE----- --hHWLQfXTYDoKhP50--
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